diff --git a/autogen.sh b/autogen.sh
index ac1a29a2dbd..057c852158b 100755
--- a/autogen.sh
+++ b/autogen.sh
@@ -237,12 +237,23 @@ set_externals() {
 check_python3() {
     echo_n "Checking for Python 3... "
     PYTHON=
-    if test 3 = `python -c 'import sys; print(sys.version_info[0])' 2> /dev/null || echo "0"`; then
-        PYTHON=python
-    fi
 
-    if test -z "$PYTHON" -a 3 = `python3 -c 'import sys; print(sys.version_info[0])' 2> /dev/null || echo "0"`; then
-        PYTHON=python3
+    python_one_liner="import sys; print(sys.version_info[0])"
+    PYTHON_PATH=`command -v python`
+    if test "x$PYTHON_PATH" != x ; then
+        version=`$PYTHON_PATH -c "$python_one_liner"`
+        if test "$version" = 3 ; then
+            PYTHON=$PYTHON_PATH
+        fi
+    fi
+    if test "x$PYTHON" = x ; then
+        PYTHON_PATH=`command -v python3`
+        if test "x$PYTHON_PATH" != x ; then
+            version=`$PYTHON_PATH -c "$python_one_liner"`
+            if test "$version" = 3 ; then
+                PYTHON=$PYTHON_PATH
+            fi
+        fi
     fi
 
     if test -z "$PYTHON" ; then
diff --git a/confdb/aclocal_misc.m4 b/confdb/aclocal_misc.m4
index 417531cdf40..6e810b9c307 100644
--- a/confdb/aclocal_misc.m4
+++ b/confdb/aclocal_misc.m4
@@ -3,17 +3,33 @@ dnl
 AC_DEFUN([PAC_CHECK_PYTHON],[
     AC_ARG_VAR([PYTHON], [set to Python 3])
     if test -z "$PYTHON" ; then
-        AC_MSG_CHECKING([Python 3])
         PYTHON=
         python_one_liner="import sys; print(sys.version_info[[0]])"
-        if test 3 = `python -c "$python_one_liner"`; then
-            PYTHON=python
-        elif test 3 = `python3 -c "$python_one_liner"`; then
-            PYTHON=python3
+
+        dnl check command 'python'
+        PYTHON_PATH=
+        AC_PATH_PROG(PYTHON_PATH, python)
+        if test "x$PYTHON_PATH" != x ; then
+            py_version=`$PYTHON_PATH -c "$python_one_liner"`
+            if test "x$py_version" = x3 ; then
+                PYTHON=$PYTHON_PATH
+            fi
+        fi
+        dnl PYTHON is still not set, check command 'python3'
+        if test "x$PYTHON" = x ; then
+            PYTHON3_PATH=
+            AC_PATH_PROG(PYTHON3_PATH, python3)
+            if test "x$PYTHON3_PATH" != x ; then
+                py3_version=`$PYTHON3_PATH -c "$python_one_liner"`
+                if test "x$py3_version" = x3 ; then
+                    PYTHON=$PYTHON3_PATH
+                fi
+            fi
         fi
-        AC_MSG_RESULT($PYTHON)
         if test -z "$PYTHON" ; then
-            AC_MSG_WARN([Python 3 not found! Bindings need to be generated before configure.])
+            AC_MSG_WARN([Python version 3 not found! Bindings need to be generated before configure.])
+        else
+            AC_MSG_NOTICE([Python version 3 is $PYTHON])
         fi
     fi
 ])
diff --git a/configure.ac b/configure.ac
index 785d33d3a3a..2e0a6f409a4 100644
--- a/configure.ac
+++ b/configure.ac
@@ -626,7 +626,6 @@ AC_CANONICAL_TARGET
 # We also need to do this before the F77 and FC test to ensure that we
 # find the C preprocessor reliably.
 AC_PROG_CC
-AC_PROG_CC_C99
 AM_PROG_CC_C_O dnl needed for automake "silent-rules"
 PAC_PUSH_FLAG([CFLAGS])
 AC_PROG_CPP
diff --git a/maint/fcrosscompile/configure.ac b/maint/fcrosscompile/configure.ac
index 15a729368c1..1a76c81d97e 100644
--- a/maint/fcrosscompile/configure.ac
+++ b/maint/fcrosscompile/configure.ac
@@ -12,7 +12,6 @@ AC_ARG_WITH(aint-size,
 
 AC_PROG_CPP
 AC_PROG_CC
-AC_PROG_CC_C99
 AC_CHECK_SIZEOF([char])
 AC_CHECK_SIZEOF([short])
 AC_CHECK_SIZEOF([int])
diff --git a/maint/local_python/binding_f08.py b/maint/local_python/binding_f08.py
index 658dc7b06bc..d499fc97565 100644
--- a/maint/local_python/binding_f08.py
+++ b/maint/local_python/binding_f08.py
@@ -322,7 +322,12 @@ def process_index(p):
         if p['param_direction'] == 'in' or p['param_direction'] == 'inout':
             convert_list_pre.append("%s = %s - 1" % (arg, p['name']))
         if p['param_direction'] == 'out' or p['param_direction'] == 'inout':
-            convert_list_post.append("%s = %s + 1" % (p['name'], arg))
+            uses['MPI_UNDEFINED'] = 1
+            convert_list_post.append("IF (%s == MPI_UNDEFINED) THEN" % arg)
+            convert_list_post.append("    %s = %s" % (p['name'], arg))
+            convert_list_post.append("ELSE")
+            convert_list_post.append("    %s = %s + 1" % (p['name'], arg))
+            convert_list_post.append("END IF")
         return (arg, arg)
 
     def process_string(p):
diff --git a/src/mpi/romio/adio/common/flatten.c b/src/mpi/romio/adio/common/flatten.c
index 12607d2ebec..9d233cd5764 100644
--- a/src/mpi/romio/adio/common/flatten.c
+++ b/src/mpi/romio/adio/common/flatten.c
@@ -182,6 +182,9 @@ static void flatlist_node_grow(ADIOI_Flatlist_node * flat, int idx)
     }
 }
 
+static MPI_Count ADIOI_Count_contiguous_blocks(MPI_Datatype datatype, MPI_Count * curr_index);
+static void ADIOI_Flatten(MPI_Datatype datatype, ADIOI_Flatlist_node * flat,
+                          ADIO_Offset st_offset, MPI_Count * curr_index);
 static void ADIOI_Optimize_flattened(ADIOI_Flatlist_node * flat_type);
 /* flatten datatype and add it to Flatlist */
 static ADIOI_Flatlist_node *ADIOI_Flatten_datatype(MPI_Datatype datatype)
diff --git a/src/mpi/romio/configure.ac b/src/mpi/romio/configure.ac
index affb3bf4e11..7d4c338e631 100644
--- a/src/mpi/romio/configure.ac
+++ b/src/mpi/romio/configure.ac
@@ -31,7 +31,6 @@ AM_MAINTAINER_MODE([enable])
 
 dnl must come before LT_INIT, which AC_REQUIREs AC_PROG_CC
 AC_PROG_CC
-AC_PROG_CC_C99
 AM_PROG_CC_C_O
 PAC_CHECK_VISIBILITY
 AC_SUBST(VISIBILITY_CFLAGS)
diff --git a/src/mpid/ch4/netmod/ofi/init_settings.c b/src/mpid/ch4/netmod/ofi/init_settings.c
index 497d254e7c6..a76757df240 100644
--- a/src/mpid/ch4/netmod/ofi/init_settings.c
+++ b/src/mpid/ch4/netmod/ofi/init_settings.c
@@ -187,7 +187,9 @@ int MPIDI_OFI_init_hints(struct fi_info *hints)
         }
     }
     hints->tx_attr->op_flags = FI_COMPLETION;
+    /* apply SAS hint to both tx and rx or else ordering may not be guaranteed */
     hints->tx_attr->msg_order = FI_ORDER_SAS;
+    hints->rx_attr->msg_order = FI_ORDER_SAS;
     /* direct RMA operations supported only with delivery complete mode,
      * else (AM mode) delivery complete is not required */
     if (MPIDI_OFI_ENABLE_RMA || MPIDI_OFI_ENABLE_ATOMICS) {
diff --git a/src/mpid/ch4/netmod/ofi/ofi_nic.c b/src/mpid/ch4/netmod/ofi/ofi_nic.c
index 8ab3ea5c1be..31c2baeb622 100644
--- a/src/mpid/ch4/netmod/ofi/ofi_nic.c
+++ b/src/mpid/ch4/netmod/ofi/ofi_nic.c
@@ -80,18 +80,22 @@ bool MPIDI_OFI_nic_already_used(const struct fi_info * prov, struct fi_info ** o
 
 /* Setup the multi-NIC data structures to use the fi_info structure given in prov */
 static int setup_single_nic(void);
+#ifdef HAVE_LIBFABRIC_NIC
 static int setup_multi_nic(int nic_count);
+#endif
 
 int MPIDI_OFI_init_multi_nic(struct fi_info *prov)
 {
     int mpi_errno = MPI_SUCCESS;
     int nic_count = 0;
-    int max_nics = MPIR_CVAR_CH4_OFI_MAX_NICS;
 
+#ifdef HAVE_LIBFABRIC_NIC
+    int max_nics = MPIR_CVAR_CH4_OFI_MAX_NICS;
     if (MPIR_CVAR_CH4_OFI_MAX_NICS == 0 || MPIR_CVAR_CH4_OFI_MAX_NICS <= -2) {
         /* Invalid values for the CVAR will default to single nic */
         max_nics = 1;
     }
+#endif
 
     /* Count the number of NICs */
     struct fi_info *first_prov = NULL;
diff --git a/src/mpid/ch4/src/mpidig_win.h b/src/mpid/ch4/src/mpidig_win.h
index b346868bfb5..6353bf7def3 100644
--- a/src/mpid/ch4/src/mpidig_win.h
+++ b/src/mpid/ch4/src/mpidig_win.h
@@ -537,7 +537,7 @@ MPL_STATIC_INLINE_PREFIX int MPIDIG_mpi_win_fence(int massert, MPIR_Win * win)
 MPL_STATIC_INLINE_PREFIX int MPIDIG_win_shared_query_self(MPIR_Win * win, int rank, MPI_Aint * size,
                                                           int *disp_unit, void *baseptr)
 {
-    if (rank == win->comm_ptr->rank) {
+    if (rank == win->comm_ptr->rank || (rank == MPI_PROC_NULL && win->comm_ptr->local_size == 1)) {
         *size = win->size;
         *disp_unit = win->disp_unit;
         *((void **) baseptr) = win->base;
diff --git a/src/mpl/configure.ac b/src/mpl/configure.ac
index c14296be381..1d769aaa5bb 100644
--- a/src/mpl/configure.ac
+++ b/src/mpl/configure.ac
@@ -16,7 +16,6 @@ AM_INIT_AUTOMAKE([subdir-objects] [-Wall -Werror foreign 1.12.3])
 
 dnl must come before LT_INIT, which AC_REQUIREs AC_PROG_CC
 AC_PROG_CC
-AC_PROG_CC_C99
 AM_PROG_CC_C_O
 
 AC_USE_SYSTEM_EXTENSIONS
diff --git a/src/mpl/src/sock/mpl_host.c b/src/mpl/src/sock/mpl_host.c
index 2be8956d002..e71463caf21 100644
--- a/src/mpl/src/sock/mpl_host.c
+++ b/src/mpl/src/sock/mpl_host.c
@@ -11,15 +11,24 @@
 #define MAX_HOSTNAME_LEN MAXHOSTNAMELEN
 #endif
 
+/* we use a static array here to avoid cleaning up (e.g. with uthash) */
 #define MAX_LOCAL_HOSTNAMES  (100)
 static char lhost[MAX_LOCAL_HOSTNAMES][MAX_HOSTNAME_LEN];
 static int lhost_count = 0;
 
 static void append_lhost(const char *host)
 {
-    int i;
+    if (lhost_count == MAX_LOCAL_HOSTNAMES) {
+        /* For the rare case when there are more than 100 local IP
+         * addresses, we only check against the first 100.
+         *
+         * MPL_host_is_local is only used in Hydra, and it is not
+         * fatal to miss some localhost detections.
+         */
+        return;
+    }
 
-    for (i = 0; i < lhost_count; i++)
+    for (int i = 0; i < lhost_count; i++)
         if (!strcmp(lhost[i], host))
             return;
 
diff --git a/src/pm/hydra/configure.ac b/src/pm/hydra/configure.ac
index 695341c85d7..d626776d08e 100644
--- a/src/pm/hydra/configure.ac
+++ b/src/pm/hydra/configure.ac
@@ -21,7 +21,6 @@ AC_ARG_PROGRAM
 dnl must come before LT_INIT, which AC_REQUIREs AC_PROG_CC
 dnl must also come before AC_USE_SYSTEM_EXTENSIONS
 AC_PROG_CC
-AC_PROG_CC_C99
 AM_PROG_CC_C_O
 
 # also needed by hwloc in embedded mode, must also come early for expansion
diff --git a/src/pm/hydra/lib/tools/bootstrap/external/ll.h b/src/pm/hydra/lib/tools/bootstrap/external/ll.h
index 3bdd16c6664..7fe23a4dced 100644
--- a/src/pm/hydra/lib/tools/bootstrap/external/ll.h
+++ b/src/pm/hydra/lib/tools/bootstrap/external/ll.h
@@ -15,6 +15,6 @@ HYD_status HYDT_bscd_ll_launch_procs(char **args, struct HYD_proxy *proxy_list,
 HYD_status HYDT_bscd_ll_query_proxy_id(int *proxy_id);
 HYD_status HYDT_bscd_ll_query_native_int(int *ret);
 HYD_status HYDT_bscd_ll_query_node_list(struct HYD_node **node_list);
-HYD_status HYDT_bscd_ll_query_env_inherit(const char *env_name, int *ret);
+HYD_status HYDT_bscd_ll_query_env_inherit(const char *env_name, int *should_inherit);
 
 #endif /* LL_H_INCLUDED */
diff --git a/src/pm/hydra/lib/tools/bootstrap/external/ll_env.c b/src/pm/hydra/lib/tools/bootstrap/external/ll_env.c
index 4997262bdc6..be0793443c8 100644
--- a/src/pm/hydra/lib/tools/bootstrap/external/ll_env.c
+++ b/src/pm/hydra/lib/tools/bootstrap/external/ll_env.c
@@ -7,7 +7,7 @@
 #include "bsci.h"
 #include "common.h"
 
-HYD_status HYDT_bscd_ll_query_env_inherit(const char *env_name, int *ret)
+HYD_status HYDT_bscd_ll_query_env_inherit(const char *env_name, int *should_inherit)
 {
     const char *env_list[] = { "LOADL_STEP_CLASS", "LOADL_STEP_ARGS",
         "LOADL_STEP_ID", "LOADL_STARTD_PORT",
@@ -49,7 +49,7 @@ HYD_status HYDT_bscd_ll_query_env_inherit(const char *env_name, int *ret)
 
     HYDU_FUNC_ENTER();
 
-    *ret = !HYDTI_bscd_in_env_list(env_name, env_list);
+    *should_inherit = !HYDTI_bscd_in_env_list(env_name, env_list);
 
     HYDU_FUNC_EXIT();
 
diff --git a/src/pm/hydra/lib/tools/bootstrap/external/lsf.h b/src/pm/hydra/lib/tools/bootstrap/external/lsf.h
index e955c79726f..a4115e07bd9 100644
--- a/src/pm/hydra/lib/tools/bootstrap/external/lsf.h
+++ b/src/pm/hydra/lib/tools/bootstrap/external/lsf.h
@@ -10,6 +10,6 @@
 
 HYD_status HYDT_bscd_lsf_query_native_int(int *ret);
 HYD_status HYDT_bscd_lsf_query_node_list(struct HYD_node **node_list);
-HYD_status HYDT_bscd_lsf_query_env_inherit(const char *env_name, int *ret);
+HYD_status HYDT_bscd_lsf_query_env_inherit(const char *env_name, int *should_inherit);
 
 #endif /* LSF_H_INCLUDED */
diff --git a/src/pm/hydra/lib/tools/bootstrap/external/lsf_env.c b/src/pm/hydra/lib/tools/bootstrap/external/lsf_env.c
index 5f9df2a64b9..c243b51c453 100644
--- a/src/pm/hydra/lib/tools/bootstrap/external/lsf_env.c
+++ b/src/pm/hydra/lib/tools/bootstrap/external/lsf_env.c
@@ -7,7 +7,7 @@
 #include "bsci.h"
 #include "common.h"
 
-HYD_status HYDT_bscd_lsf_query_env_inherit(const char *env_name, int *ret)
+HYD_status HYDT_bscd_lsf_query_env_inherit(const char *env_name, int *should_inherit)
 {
     const char *env_list[] = { "DISPLAY", "EGO_SERVERDIR", "LSB_TRAPSIGS",
         "LSF_SERVERDIR", "HOSTTYPE", "LSB_HOSTS",
@@ -30,7 +30,7 @@ HYD_status HYDT_bscd_lsf_query_env_inherit(const char *env_name, int *ret)
 
     HYDU_FUNC_ENTER();
 
-    *ret = !HYDTI_bscd_in_env_list(env_name, env_list);
+    *should_inherit = !HYDTI_bscd_in_env_list(env_name, env_list);
 
     HYDU_FUNC_EXIT();
 
diff --git a/src/pm/hydra/lib/tools/bootstrap/external/pbs.h b/src/pm/hydra/lib/tools/bootstrap/external/pbs.h
index 6d07f82d391..49956520ab9 100644
--- a/src/pm/hydra/lib/tools/bootstrap/external/pbs.h
+++ b/src/pm/hydra/lib/tools/bootstrap/external/pbs.h
@@ -21,7 +21,7 @@ extern struct HYDT_bscd_pbs_sys_s *HYDT_bscd_pbs_sys;
 
 HYD_status HYDT_bscd_pbs_launch_procs(char **args, struct HYD_proxy *proxy_list, int num_hosts,
                                       int use_rmk, int *control_fd);
-HYD_status HYDT_bscd_pbs_query_env_inherit(const char *env_name, int *ret);
+HYD_status HYDT_bscd_pbs_query_env_inherit(const char *env_name, int *should_inherit);
 HYD_status HYDT_bscd_pbs_wait_for_completion(int timeout);
 HYD_status HYDT_bscd_pbs_launcher_finalize(void);
 #endif /* if defined(HAVE_TM_H) */
diff --git a/src/pm/hydra/lib/tools/bootstrap/external/pbs_env.c b/src/pm/hydra/lib/tools/bootstrap/external/pbs_env.c
index 403b69686bb..4dc9d6966e3 100644
--- a/src/pm/hydra/lib/tools/bootstrap/external/pbs_env.c
+++ b/src/pm/hydra/lib/tools/bootstrap/external/pbs_env.c
@@ -7,7 +7,7 @@
 #include "common.h"
 #include "pbs.h"
 
-HYD_status HYDT_bscd_pbs_query_env_inherit(const char *env_name, int *ret)
+HYD_status HYDT_bscd_pbs_query_env_inherit(const char *env_name, int *should_inherit)
 {
     const char *env_list[] = { "PBSCOREDUMP",
         "PBSDEBUG",
@@ -47,7 +47,7 @@ HYD_status HYDT_bscd_pbs_query_env_inherit(const char *env_name, int *ret)
 
     HYDU_FUNC_ENTER();
 
-    *ret = !HYDTI_bscd_in_env_list(env_name, env_list);
+    *should_inherit = !HYDTI_bscd_in_env_list(env_name, env_list);
 
     HYDU_FUNC_EXIT();
 
diff --git a/src/pm/hydra/lib/tools/bootstrap/external/rsh.h b/src/pm/hydra/lib/tools/bootstrap/external/rsh.h
index 8cb213f63c9..292cfd017e5 100644
--- a/src/pm/hydra/lib/tools/bootstrap/external/rsh.h
+++ b/src/pm/hydra/lib/tools/bootstrap/external/rsh.h
@@ -8,6 +8,6 @@
 
 #include "hydra.h"
 
-HYD_status HYDT_bscd_rsh_query_env_inherit(const char *env_name, int *ret);
+HYD_status HYDT_bscd_rsh_query_env_inherit(const char *env_name, int *should_inherit);
 
 #endif /* RSH_H_INCLUDED */
diff --git a/src/pm/hydra/lib/tools/bootstrap/external/rsh_env.c b/src/pm/hydra/lib/tools/bootstrap/external/rsh_env.c
index 249c5872b2e..bb6dc763856 100644
--- a/src/pm/hydra/lib/tools/bootstrap/external/rsh_env.c
+++ b/src/pm/hydra/lib/tools/bootstrap/external/rsh_env.c
@@ -7,13 +7,13 @@
 #include "bsci.h"
 #include "common.h"
 
-HYD_status HYDT_bscd_rsh_query_env_inherit(const char *env_name, int *ret)
+HYD_status HYDT_bscd_rsh_query_env_inherit(const char *env_name, int *should_inherit)
 {
     const char *env_list[] = { "DISPLAY", NULL };
 
     HYDU_FUNC_ENTER();
 
-    *ret = !HYDTI_bscd_in_env_list(env_name, env_list);
+    *should_inherit = !HYDTI_bscd_in_env_list(env_name, env_list);
 
     HYDU_FUNC_EXIT();
 
diff --git a/src/pm/hydra/lib/tools/bootstrap/external/sge.h b/src/pm/hydra/lib/tools/bootstrap/external/sge.h
index 42bc6423b50..038710c72d4 100644
--- a/src/pm/hydra/lib/tools/bootstrap/external/sge.h
+++ b/src/pm/hydra/lib/tools/bootstrap/external/sge.h
@@ -10,6 +10,6 @@
 
 HYD_status HYDT_bscd_sge_query_native_int(int *ret);
 HYD_status HYDT_bscd_sge_query_node_list(struct HYD_node **node_list);
-HYD_status HYDT_bscd_sge_query_env_inherit(const char *env_name, int *ret);
+HYD_status HYDT_bscd_sge_query_env_inherit(const char *env_name, int *should_inherit);
 
 #endif /* SGE_H_INCLUDED */
diff --git a/src/pm/hydra/lib/tools/bootstrap/external/sge_env.c b/src/pm/hydra/lib/tools/bootstrap/external/sge_env.c
index 689a0d1d54b..b8c8b34aadf 100644
--- a/src/pm/hydra/lib/tools/bootstrap/external/sge_env.c
+++ b/src/pm/hydra/lib/tools/bootstrap/external/sge_env.c
@@ -7,7 +7,7 @@
 #include "bsci.h"
 #include "common.h"
 
-HYD_status HYDT_bscd_sge_query_env_inherit(const char *env_name, int *ret)
+HYD_status HYDT_bscd_sge_query_env_inherit(const char *env_name, int *should_inherit)
 {
     const char *env_list[] = { "DISPLAY", "SGE_ROOT", "SGE_CELL", "SGE_DEBUG_LEVEL",
         "SGE_QMASTER_PORT", "SGE_O_HOME", "SGE_O_HOST",
@@ -26,7 +26,7 @@ HYD_status HYDT_bscd_sge_query_env_inherit(const char *env_name, int *ret)
 
     HYDU_FUNC_ENTER();
 
-    *ret = !HYDTI_bscd_in_env_list(env_name, env_list);
+    *should_inherit = !HYDTI_bscd_in_env_list(env_name, env_list);
 
     HYDU_FUNC_EXIT();
 
diff --git a/src/pm/hydra/lib/tools/bootstrap/external/slurm.h b/src/pm/hydra/lib/tools/bootstrap/external/slurm.h
index 026762fb4ed..a351a34507e 100644
--- a/src/pm/hydra/lib/tools/bootstrap/external/slurm.h
+++ b/src/pm/hydra/lib/tools/bootstrap/external/slurm.h
@@ -13,6 +13,6 @@ HYD_status HYDT_bscd_slurm_launch_procs(char **args, struct HYD_proxy *proxy_lis
 HYD_status HYDT_bscd_slurm_query_proxy_id(int *proxy_id);
 HYD_status HYDT_bscd_slurm_query_native_int(int *ret);
 HYD_status HYDT_bscd_slurm_query_node_list(struct HYD_node **node_list);
-HYD_status HYDT_bscd_slurm_query_env_inherit(const char *env_name, int *ret);
+HYD_status HYDT_bscd_slurm_query_env_inherit(const char *env_name, int *should_inherit);
 
 #endif /* SLURM_H_INCLUDED */
diff --git a/src/pm/hydra/lib/tools/bootstrap/external/slurm_env.c b/src/pm/hydra/lib/tools/bootstrap/external/slurm_env.c
index 05380b004f9..50f22a9b93f 100644
--- a/src/pm/hydra/lib/tools/bootstrap/external/slurm_env.c
+++ b/src/pm/hydra/lib/tools/bootstrap/external/slurm_env.c
@@ -7,16 +7,16 @@
 #include "bsci.h"
 #include "common.h"
 
-HYD_status HYDT_bscd_slurm_query_env_inherit(const char *env_name, int *ret)
+HYD_status HYDT_bscd_slurm_query_env_inherit(const char *env_name, int *should_inherit)
 {
     HYDU_FUNC_ENTER();
 
     /* check if envvar starts with SBATCH_, SLURMD_, or SLURM_ */
     if (strncmp(env_name, "SBATCH_", 7) == 0 || strncmp(env_name, "SLURMD_", 7) == 0 ||
         strncmp(env_name, "SLURM_", 6) == 0) {
-        *ret = 1;
+        *should_inherit = 0;
     } else {
-        *ret = 0;
+        *should_inherit = 1;
     }
 
     HYDU_FUNC_EXIT();
diff --git a/src/pm/hydra/lib/tools/bootstrap/external/ssh.h b/src/pm/hydra/lib/tools/bootstrap/external/ssh.h
index 382fd3718f1..752f27c8f41 100644
--- a/src/pm/hydra/lib/tools/bootstrap/external/ssh.h
+++ b/src/pm/hydra/lib/tools/bootstrap/external/ssh.h
@@ -32,7 +32,7 @@ extern struct HYDT_bscd_ssh_time *HYDT_bscd_ssh_time;
 
 HYD_status HYDTI_bscd_ssh_store_launch_time(char *hostname);
 
-HYD_status HYDT_bscd_ssh_query_env_inherit(const char *env_name, int *ret);
+HYD_status HYDT_bscd_ssh_query_env_inherit(const char *env_name, int *should_inherit);
 HYD_status HYDT_bscd_ssh_launcher_finalize(void);
 
 #endif /* SSH_H_INCLUDED */
diff --git a/src/pm/hydra/lib/tools/bootstrap/external/ssh_env.c b/src/pm/hydra/lib/tools/bootstrap/external/ssh_env.c
index f34fc0b5054..f53467c437c 100644
--- a/src/pm/hydra/lib/tools/bootstrap/external/ssh_env.c
+++ b/src/pm/hydra/lib/tools/bootstrap/external/ssh_env.c
@@ -7,13 +7,13 @@
 #include "bsci.h"
 #include "common.h"
 
-HYD_status HYDT_bscd_ssh_query_env_inherit(const char *env_name, int *ret)
+HYD_status HYDT_bscd_ssh_query_env_inherit(const char *env_name, int *should_inherit)
 {
     const char *env_list[] = { "DISPLAY", NULL };
 
     HYDU_FUNC_ENTER();
 
-    *ret = !HYDTI_bscd_in_env_list(env_name, env_list);
+    *should_inherit = !HYDTI_bscd_in_env_list(env_name, env_list);
 
     HYDU_FUNC_EXIT();
 
diff --git a/src/pm/hydra/lib/tools/bootstrap/include/bsci.h b/src/pm/hydra/lib/tools/bootstrap/include/bsci.h
index 957801eefc6..22873ee1fa2 100644
--- a/src/pm/hydra/lib/tools/bootstrap/include/bsci.h
+++ b/src/pm/hydra/lib/tools/bootstrap/include/bsci.h
@@ -63,7 +63,7 @@ struct HYDT_bsci_fns {
     HYD_status(*query_proxy_id) (int *proxy_id);
 
     /** \brief Query if an environment variable should be inherited */
-    HYD_status(*query_env_inherit) (const char *env_name, int *ret);
+    HYD_status(*query_env_inherit) (const char *env_name, int *should_inherit);
 };
 
 /** \cond */
@@ -186,7 +186,7 @@ HYD_status HYDT_bsci_query_proxy_id(int *proxy_id);
  * from the user's environment is safe to be propagated to the remote
  * processes.
  */
-HYD_status HYDT_bsci_query_env_inherit(const char *env_name, int *ret);
+HYD_status HYDT_bsci_query_env_inherit(const char *env_name, int *should_inherit);
 
 /**
  * \brief HYDT_bsci_query_native_int - Query if the RMK integrates
diff --git a/src/pm/hydra/lib/utils/env.c b/src/pm/hydra/lib/utils/env.c
index df78d506b45..9bc8aaef9a5 100644
--- a/src/pm/hydra/lib/utils/env.c
+++ b/src/pm/hydra/lib/utils/env.c
@@ -39,37 +39,29 @@ HYD_status HYDU_env_to_str(struct HYD_env *env, char **str)
 
 HYD_status HYDU_list_inherited_env(struct HYD_env **env_list)
 {
-    char *env_str = NULL, *env_name;
-    int i, ret;
     HYD_status status = HYD_SUCCESS;
 
     HYDU_FUNC_ENTER();
 
     *env_list = NULL;
-    i = 0;
-    while (environ[i]) {
+    for (int i = 0; environ[i]; i++) {
+        char *env_str, *env_name;
+        int should_inherit;
+
         env_str = MPL_strdup(environ[i]);
         env_name = strtok(env_str, "=");
 
-        status = HYDT_bsci_query_env_inherit(env_name, &ret);
-        HYDU_ERR_POP(status, "error querying environment propagation\n");
-
+        status = HYDT_bsci_query_env_inherit(env_name, &should_inherit);
         MPL_free(env_str);
-        env_str = NULL;
+        HYDU_ERR_POP(status, "error querying environment propagation\n");
 
-        if (!ret) {
-            i++;
-            continue;
+        if (should_inherit) {
+            status = HYDU_append_env_str_to_list(environ[i], env_list);
+            HYDU_ERR_POP(status, "unable to add env to list\n");
         }
-
-        status = HYDU_append_env_str_to_list(environ[i], env_list);
-        HYDU_ERR_POP(status, "unable to add env to list\n");
-
-        i++;
     }
 
   fn_exit:
-    MPL_free(env_str);
     HYDU_FUNC_EXIT();
     return status;
 
diff --git a/src/pmi/configure.ac b/src/pmi/configure.ac
index eca0ff6efd6..c4aef0c30f9 100644
--- a/src/pmi/configure.ac
+++ b/src/pmi/configure.ac
@@ -16,7 +16,6 @@ m4_ifdef([AM_SILENT_RULES], [AM_SILENT_RULES([yes])])
 AM_PROG_AR
 
 AC_PROG_CC
-AC_PROG_CC_C99
 AM_PROG_CC_C_O
 
 PAC_C_NO_COMMON
diff --git a/src/pmi/src/pmix.c b/src/pmi/src/pmix.c
index 9cda26dff85..3dce70dea06 100644
--- a/src/pmi/src/pmix.c
+++ b/src/pmi/src/pmix.c
@@ -399,11 +399,13 @@ pmix_status_t PMIx_Resolve_peers(const char *nodename,
                                  const pmix_nspace_t nspace, pmix_proc_t ** procs, size_t * nprocs)
 {
     assert(0);
+    return PMIX_SUCCESS;
 }
 
 pmix_status_t PMIx_Resolve_nodes(const pmix_nspace_t nspace, char **nodelist)
 {
     assert(0);
+    return PMIX_SUCCESS;
 }
 
 const char *PMIx_Error_string(pmix_status_t status)
@@ -415,6 +417,7 @@ pmix_status_t PMIx_Spawn(const pmix_info_t job_info[], size_t ninfo,
                          const pmix_app_t apps[], size_t napps, pmix_nspace_t nspace)
 {
     assert(0);
+    return PMIX_SUCCESS;
 }
 
 /* convert predefined keys/attributes to the server format */
diff --git a/src/util/mpir_pmi.c b/src/util/mpir_pmi.c
index d3fb776c337..f567cac624a 100644
--- a/src/util/mpir_pmi.c
+++ b/src/util/mpir_pmi.c
@@ -142,7 +142,7 @@ int MPIR_pmi_init(void)
     MPL_env2int("PMI_VERSION", &pmi_version);
     MPL_env2int("PMI_SUBVERSION", &pmi_subversion);
 
-    int has_parent, rank, size, appnum;
+    int has_parent, rank, size, appnum = -1;
     SWITCH_PMI(mpi_errno = pmi1_init(&has_parent, &rank, &size, &appnum),
                mpi_errno = pmi2_init(&has_parent, &rank, &size, &appnum),
                mpi_errno = pmix_init(&has_parent, &rank, &size, &appnum));
diff --git a/src/util/mpir_pmix.inc b/src/util/mpir_pmix.inc
index 089fded51b3..3f3afa859ce 100644
--- a/src/util/mpir_pmix.inc
+++ b/src/util/mpir_pmix.inc
@@ -93,11 +93,14 @@ static int pmix_init(int *has_parent, int *rank, int *size, int *appnum)
 
     /* Get the appnum */
     pmi_errno = PMIx_Get(&pmix_proc, PMIX_APPNUM, NULL, 0, &pvalue);
-    MPIR_ERR_CHKANDJUMP1(pmi_errno != PMIX_SUCCESS, mpi_errno, MPI_ERR_OTHER,
-                         "**pmix_get", "**pmix_get %s", PMIx_Error_string(pmi_errno));
-    MPIR_Assert(pvalue->data.uint32 <= INT_MAX);        /* overflow check */
-    *appnum = (int) pvalue->data.uint32;
-    PMIX_VALUE_RELEASE(pvalue);
+    if (pmi_errno != PMIX_ERR_NOT_FOUND) {
+        MPIR_ERR_CHKANDJUMP1(pmi_errno != PMIX_SUCCESS, mpi_errno, MPI_ERR_OTHER,
+                             "**pmix_get", "**pmix_get %s", PMIx_Error_string(pmi_errno));
+        MPIR_Assert(pvalue->data.uint32 <= INT_MAX);    /* overflow check */
+        *appnum = (int) pvalue->data.uint32;
+        PMIX_VALUE_RELEASE(pvalue);
+    }
+
     pmix_value_t value;
     pmix_value_t *val = &value;
 
@@ -219,14 +222,25 @@ static int pmix_get_parent(const char *key, char *val, int val_size)
 
 static bool pmix_get_jobattr(const char *key, char *valbuf)
 {
+    bool found = false;
     pmix_value_t *pvalue;
-    int pmi_errno = PMIx_Get(NULL, key, NULL, 0, &pvalue);
-    if (pmi_errno != PMIX_SUCCESS) {
-        return false;
+
+    /* if this is a non-reserved key, we want to make sure not to block
+     * by using PMIX_IMMEDIATE */
+    pmix_info_t *info;
+    PMIX_INFO_CREATE(info, 1);
+    int flag = 1;
+    PMIx_Info_load(info, PMIX_IMMEDIATE, &flag, PMIX_BOOL);
+
+    int pmi_errno = PMIx_Get(NULL, key, info, 1, &pvalue);
+    if (pmi_errno == PMIX_SUCCESS) {
+        strncpy(valbuf, pvalue->data.string, pmi_max_val_size);
+        PMIX_VALUE_RELEASE(pvalue);
+        found = true;
     }
-    strncpy(valbuf, pvalue->data.string, pmi_max_val_size);
-    PMIX_VALUE_RELEASE(pvalue);
-    return true;
+    PMIX_INFO_FREE(info, 1);
+
+    return found;
 }
 
 static int pmix_barrier(void)
diff --git a/test/mpi/autogen.sh b/test/mpi/autogen.sh
index e363e27bb42..b23ef4205ef 100755
--- a/test/mpi/autogen.sh
+++ b/test/mpi/autogen.sh
@@ -12,12 +12,23 @@ echo_n() {
 check_python3() {
     echo_n "Checking for Python 3... "
     PYTHON=
-    if test 3 = `python -c 'import sys; print(sys.version_info[0])' 2> /dev/null || echo "0"`; then
-        PYTHON=python
-    fi
 
-    if test -z "$PYTHON" -a 3 = `python3 -c 'import sys; print(sys.version_info[0])' 2> /dev/null || echo "0"`; then
-        PYTHON=python3
+    python_one_liner="import sys; print(sys.version_info[0])"
+    PYTHON_PATH=`command -v python`
+    if test "x$PYTHON_PATH" != x ; then
+        version=`$PYTHON_PATH -c "$python_one_liner"`
+        if test "$version" = 3 ; then
+            PYTHON=$PYTHON_PATH
+        fi
+    fi
+    if test "x$PYTHON" = x ; then
+        PYTHON_PATH=`command -v python3`
+        if test "x$PYTHON_PATH" != x ; then
+            version=`$PYTHON_PATH -c "$python_one_liner"`
+            if test "$version" = 3 ; then
+                PYTHON=$PYTHON_PATH
+            fi
+        fi
     fi
 
     if test -z "$PYTHON" ; then
diff --git a/test/mpi/configure.ac b/test/mpi/configure.ac
index 826d8deda40..84a75f0726f 100644
--- a/test/mpi/configure.ac
+++ b/test/mpi/configure.ac
@@ -416,7 +416,6 @@ PAC_CONFIG_SUBDIR_ARGS([dtpools])
 
 # Running C compiler tests
 AC_PROG_CC
-AC_PROG_CC_C99
 AM_PROG_CC_C_O
 
 AC_USE_SYSTEM_EXTENSIONS
diff --git a/test/mpi/dtpools/configure.ac b/test/mpi/dtpools/configure.ac
index f47b9e08c0a..e22b3a1a02c 100644
--- a/test/mpi/dtpools/configure.ac
+++ b/test/mpi/dtpools/configure.ac
@@ -31,7 +31,6 @@ fi
 # Checks for programs.
 AC_PROG_AWK
 AC_PROG_CC
-AC_PROG_CC_C99
 AC_PROG_CPP
 AC_PROG_INSTALL
 AC_PROG_LN_S
diff --git a/test/mpi/io/i_noncontig_coll2.c b/test/mpi/io/i_noncontig_coll2.c
index 3714fc58b12..390c3ddc82e 100644
--- a/test/mpi/io/i_noncontig_coll2.c
+++ b/test/mpi/io/i_noncontig_coll2.c
@@ -75,7 +75,7 @@ int cb_gather_name_array(MPI_Comm comm, ADIO_cb_name_array * arrayp)
      * uses a keyval to cache the name array.  We'll just rebuild it if we
      * need to */
 
-    char my_procname[MPI_MAX_PROCESSOR_NAME], **procname = 0;
+    char my_procname[MPI_MAX_PROCESSOR_NAME], **procname = 0, *procname_buffer;
     int *procname_len = NULL, my_procname_len, *disp = NULL, i;
     int commsize, commrank;
     ADIO_cb_name_array array = NULL;
@@ -121,30 +121,22 @@ int cb_gather_name_array(MPI_Comm comm, ADIO_cb_name_array * arrayp)
         }
 #endif
 
+        int len_total = 0;
+        disp = malloc((commsize + 1) * sizeof(int));
+        disp[0] = 0;
         for (i = 0; i < commsize; i++) {
             /* add one to the lengths because we need to count the
              * terminator, and we are going to use this list of lengths
              * again in the gatherv.
              */
             procname_len[i]++;
-            procname[i] = malloc(procname_len[i]);
-            if (procname[i] == NULL) {
-                return -1;
-            }
+            len_total += procname_len[i];
+            disp[i + 1] = len_total;
         }
 
-        /* create our list of displacements for the gatherv.  we're going
-         * to do everything relative to the start of the region allocated
-         * for procname[0]
-         *
-         * I suppose it is theoretically possible that the distance between
-         * malloc'd regions could be more than will fit in an int.  We don't
-         * cover that case.
-         */
-        disp = malloc(commsize * sizeof(int));
-        disp[0] = 0;
-        for (i = 1; i < commsize; i++) {
-            disp[i] = (int) (procname[i] - procname[0]);
+        procname_buffer = malloc(len_total);
+        for (i = 0; i < commsize; i++) {
+            procname[i] = procname_buffer + disp[i];
         }
     }
 
@@ -322,9 +314,10 @@ int main(int argc, char **argv)
 
     free(filename);
     free(cb_config_string);
-    for (i = 0; i < array->namect; i++)
-        free(array->names[i]);
-    free(array->names);
+    if (mynod == 0) {
+        free(array->names[0]);
+        free(array->names);
+    }
     free(array);
     MTest_Finalize(errs);
     return MTestReturnValue(errs);
diff --git a/test/mpi/rma/win_shared_query_null.c b/test/mpi/rma/win_shared_query_null.c
index 49bc2f4e059..2328ac1fe35 100644
--- a/test/mpi/rma/win_shared_query_null.c
+++ b/test/mpi/rma/win_shared_query_null.c
@@ -27,6 +27,19 @@ int main(int argc, char **argv)
 
     MTest_Init(&argc, &argv);
 
+    size = sizeof(int) * 4;
+
+    /* First test the query on self works */
+    MPI_Win_allocate_shared(size, sizeof(int), MPI_INFO_NULL, MPI_COMM_SELF, &my_base, &shm_win);
+    MPI_Win_shared_query(shm_win, MPI_PROC_NULL, &query_size, &query_disp_unit, &query_base);
+    if (query_base == NULL || query_size != size || query_disp_unit != sizeof(int)) {
+        fprintf(stderr, "Self shared query with PROC_NULL: base %p, size %ld, unit %d\n",
+                query_base, query_size, query_disp_unit);
+        errors++;
+    }
+    MPI_Win_free(&shm_win);
+
+    /* Next test the query with a true shared domain */
     MPI_Comm_rank(MPI_COMM_WORLD, &rank);
     MPI_Comm_split_type(MPI_COMM_WORLD, MPI_COMM_TYPE_SHARED, rank, MPI_INFO_NULL, &shm_comm);
 
@@ -38,8 +51,6 @@ int main(int argc, char **argv)
     if (shm_nproc < 2)
         goto exit;
 
-    size = sizeof(int) * 4;
-
     /* Allocate zero-byte window on rank 0 and non-zero for others */
     if (shm_rank == 0) {
         MPI_Win_allocate_shared(0, sizeof(int), MPI_INFO_NULL, shm_comm, &my_base, &shm_win);