For each repo stop on error (#642)

This is an early version of patches I am about to send upstream:
https://github.com/gitgitgadget/git/pull/1719.

This addresses https://github.com/microsoft/git/issues/623.

Documentation/git-for-each-repo.txt

@@ -42,6 +42,10 @@ These config values are loaded from system, global, and local Git config,
 as available. If `git for-each-repo` is run in a directory that is not a
 Git repository, then only the system and global config is used.
 
+--keep-going::
+	Continue with the remaining repositories if the command failed
+	on a repository. The exit code will still indicate that the
+	overall operation was not successful.
 
 SUBPROCESS BEHAVIOR
 -------------------

builtin/for-each-repo.c

@@ -32,6 +32,7 @@ static int run_command_on_repo(const char *path, int argc, const char ** argv)
 int cmd_for_each_repo(int argc, const char **argv, const char *prefix)
 {
 	static const char *config_key = NULL;
+	int keep_going = 0;
 	int i, result = 0;
 	const struct string_list *values;
 	int err;
@@ -39,6 +40,8 @@ int cmd_for_each_repo(int argc, const char **argv, const char *prefix)
 	const struct option options[] = {
 		OPT_STRING(0, "config", &config_key, N_("config"),
 			   N_("config key storing a list of repository paths")),
+		OPT_BOOL(0, "keep-going", &keep_going,
+			 N_("keep going even if command fails in a repository")),
 		OPT_END()
 	};
 
@@ -55,8 +58,9 @@ int cmd_for_each_repo(int argc, const char **argv, const char *prefix)
 	else if (err)
 		return 0;
 
-	for (i = 0; !result && i < values->nr; i++)
-		result = run_command_on_repo(values->items[i].string, argc, argv);
+	for (i = 0; (keep_going || !result) && i < values->nr; i++)
+		if (run_command_on_repo(values->items[i].string, argc, argv))
+			result = 1;
 
 	return result;
 }

builtin/gc.c

@@ -1917,6 +1917,7 @@ static int launchctl_schedule_plist(const char *exec_path, enum schedule_priorit
 		   "<string>--exec-path=%s</string>\n"
 		   "%s" /* For extra config parameters. */
 		   "<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"
@@ -2160,7 +2161,7 @@ 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\" %s for-each-repo --config=maintenance.repo maintenance run --schedule=%s</Arguments>\n"
+	      "<Arguments>--exec-path=\"%s\" %s for-each-repo --keep-going --config=maintenance.repo maintenance run --schedule=%s</Arguments>\n"
 	      "</Exec>\n"
 	      "</Actions>\n"
 	      "</Task>\n";
@@ -2306,7 +2307,7 @@ 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\" %s for-each-repo --config=maintenance.repo maintenance run --schedule=%%s\n",
+			    "%%d %%s * * %%s \"%s/git\" --exec-path=\"%s\" %s for-each-repo --keep-going --config=maintenance.repo maintenance run --schedule=%%s\n",
 			    exec_path, exec_path, get_extra_config_parameters());
 		fprintf(cron_in, line_format.buf, minute, "1-23", "*", "hourly");
 		fprintf(cron_in, line_format.buf, minute, "0", "1-6", "daily");
@@ -2507,7 +2508,7 @@ static int systemd_timer_write_service_template(const char *exec_path)
 	       "\n"
 	       "[Service]\n"
 	       "Type=oneshot\n"
-	       "ExecStart=\"%s/git\" --exec-path=\"%s\" %s for-each-repo --config=maintenance.repo maintenance run --schedule=%%i\n"
+	       "ExecStart=\"%s/git\" --exec-path=\"%s\" %s for-each-repo --keep-going --config=maintenance.repo maintenance run --schedule=%%i\n"
 	       "LockPersonality=yes\n"
 	       "MemoryDenyWriteExecute=yes\n"
 	       "NoNewPrivileges=yes\n"

t/t0068-for-each-repo.sh

@@ -59,4 +59,20 @@ test_expect_success 'error on NULL value for config keys' '
 	test_cmp expect actual
 '
 
+test_expect_success '--keep-going' '
+	git config keep.going non-existing &&
+	git config --add keep.going . &&
+
+	test_must_fail git for-each-repo --config=keep.going \
+		-- branch >out 2>err &&
+	test_grep "cannot change to .*non-existing" err &&
+	test_must_be_empty out &&
+
+	test_must_fail git for-each-repo --config=keep.going --keep-going \
+		-- branch >out 2>err &&
+	test_grep "cannot change to .*non-existing" err &&
+	git branch >expect &&
+	test_cmp expect out
+'
+
 test_done

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' '