maintenance: running maintenance should not stop on errors

In microsoft#623, it was reported that
maintenance stops on a missing repository, omitting the remaining
repositories that were scheduled for maintenance.

This is undesirable, as it should be a best effort type of operation.

It should still fail due to the missing repository, of course, but not
leave the non-missing repositories in unmaintained shapes.

Let's use `for-each-repo`'s shiny new `--keep-going` option that we just
introduced for that very purpose.

This change will be picked up when running `git maintenance start`,
which is run implicitly by `scalar reconfigure`.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/gc.c

@@ -1858,6 +1858,7 @@ static int launchctl_schedule_plist(const char *exec_path, enum schedule_priorit
 		   "<string>%s/git</string>\n"
 		   "<string>--exec-path=%s</string>\n"
 		   "<string>for-each-repo</string>\n"
+		   "<string>--keep-going</string>\n"
 		   "<string>--config=maintenance.repo</string>\n"
 		   "<string>maintenance</string>\n"
 		   "<string>run</string>\n"
@@ -2100,7 +2101,7 @@ static int schtasks_schedule_task(const char *exec_path, enum schedule_priority
 	      "<Actions Context=\"Author\">\n"
 	      "<Exec>\n"
 	      "<Command>\"%s\\headless-git.exe\"</Command>\n"
-	      "<Arguments>--exec-path=\"%s\" for-each-repo --config=maintenance.repo maintenance run --schedule=%s</Arguments>\n"
+	      "<Arguments>--exec-path=\"%s\" for-each-repo --keep-going --config=maintenance.repo maintenance run --schedule=%s</Arguments>\n"
 	      "</Exec>\n"
 	      "</Actions>\n"
 	      "</Task>\n";
@@ -2245,7 +2246,7 @@ static int crontab_update_schedule(int run_maintenance, int fd)
 			"# replaced in the future by a Git command.\n\n");
 
 		strbuf_addf(&line_format,
-			    "%%d %%s * * %%s \"%s/git\" --exec-path=\"%s\" for-each-repo --config=maintenance.repo maintenance run --schedule=%%s\n",
+			    "%%d %%s * * %%s \"%s/git\" --exec-path=\"%s\" for-each-repo --keep-going --config=maintenance.repo maintenance run --schedule=%%s\n",
 			    exec_path, exec_path);
 		fprintf(cron_in, line_format.buf, minute, "1-23", "*", "hourly");
 		fprintf(cron_in, line_format.buf, minute, "0", "1-6", "daily");
@@ -2446,7 +2447,7 @@ static int systemd_timer_write_service_template(const char *exec_path)
 	       "\n"
 	       "[Service]\n"
 	       "Type=oneshot\n"
-	       "ExecStart=\"%s/git\" --exec-path=\"%s\" for-each-repo --config=maintenance.repo maintenance run --schedule=%%i\n"
+	       "ExecStart=\"%s/git\" --exec-path=\"%s\" for-each-repo --keep-going --config=maintenance.repo maintenance run --schedule=%%i\n"
 	       "LockPersonality=yes\n"
 	       "MemoryDenyWriteExecute=yes\n"
 	       "NoNewPrivileges=yes\n"

t/t7900-maintenance.sh

@@ -639,9 +639,9 @@ test_expect_success 'start from empty cron table' '
 	# start registers the repo
 	git config --get --global --fixed-value maintenance.repo "$(pwd)" &&
 
-	grep "for-each-repo --config=maintenance.repo maintenance run --schedule=daily" cron.txt &&
-	grep "for-each-repo --config=maintenance.repo maintenance run --schedule=hourly" cron.txt &&
-	grep "for-each-repo --config=maintenance.repo maintenance run --schedule=weekly" cron.txt
+	grep "for-each-repo --keep-going --config=maintenance.repo maintenance run --schedule=daily" cron.txt &&
+	grep "for-each-repo --keep-going --config=maintenance.repo maintenance run --schedule=hourly" cron.txt &&
+	grep "for-each-repo --keep-going --config=maintenance.repo maintenance run --schedule=weekly" cron.txt
 '
 
 test_expect_success 'stop from existing schedule' '