From ad6a69597e96701b0006b0f0a18e6a126d7ce30a Mon Sep 17 00:00:00 2001
From: Carl Johnson <carljohnson@improbable.io>
Date: Fri, 21 Feb 2020 14:34:53 +0000
Subject: [PATCH] Fix label syncing (#154)

---
 python/checkout.py |  6 ++++--
 python/perforce.py | 20 +++++++++++++++-----
 2 files changed, 19 insertions(+), 7 deletions(-)

diff --git a/python/checkout.py b/python/checkout.py
index 8e40e5a..ca94533 100644
--- a/python/checkout.py
+++ b/python/checkout.py
@@ -36,8 +36,10 @@ def main():
 
         repo.p4print_unshelve(changelist)
 
-    revision = get_build_revision()
-    description = repo.description(get_users_changelist() or revision.strip('@'))
+    description = repo.description(
+        # Prefer users change description over latest submitted change
+        get_users_changelist() or repo.head_at_revision(revision)
+    )
     set_build_info(revision, description)
 
 
diff --git a/python/perforce.py b/python/perforce.py
index 20ebe51..06d9c65 100644
--- a/python/perforce.py
+++ b/python/perforce.py
@@ -149,15 +149,25 @@ def info(self):
     def head(self):
         """Get current head revision"""
         self._setup_client()
-        client_head = self.perforce.run_changes([
-            '-m', '1', '-s', 'submitted', '//%s/...' % self._get_clientname()])
+        # Get head based on client view (e.g. within the stream)
+        client_head = self.head_at_revision('//%s/...' % self._get_clientname())
         if client_head:
-            return client_head[0]['change']
-        # Fallback for when client view has no submitted changes
+            return client_head
+        # Fallback for when client view has no submitted changes, global head revision
         return self.perforce.run_counter("maxCommitChange")[0]['value']
 
+    def head_at_revision(self, revision):
+        """Get head submitted changelist at revision specifier"""
+        # Resolve revision specifier like "@labelname" to a concrete submitted change
+        result = self.perforce.run_changes([
+            '-m', '1', '-s', 'submitted', revision
+        ])
+        if not result:
+            return None # Revision spec had no submitted changes
+        return result[0]['change']
+
     def description(self, changelist):
-        """Get description of a given changelist"""
+        """Get description of a given changelist number"""
         return self.perforce.run_describe(str(changelist))[0]['desc']
 
     def sync(self, revision=None):