Merge branch 'ps/maintenance-start-crash-fix'

"git maintenance start" crashed due to an uninitialized variable
reference, which has been corrected.

* ps/maintenance-start-crash-fix:
  builtin/gc: fix crash when running `git maintenance start`

Author: ttaylorr

builtin/gc.c

@@ -1832,7 +1832,7 @@ static const char *get_extra_launchctl_strings(void) {
  *     | Input |                     Output                      |
  *     | *cmd  | return code |       *out        | *is_available |
  *     +-------+-------------+-------------------+---------------+
- *     | "foo" |    false    | NULL              |  (unchanged)  |
+ *     | "foo" |    false    | "foo" (allocated) |  (unchanged)  |
  *     +-------+-------------+-------------------+---------------+
  *
  *   GIT_TEST_MAINT_SCHEDULER set to “foo:./mock_foo.sh,bar:./mock_bar.sh”
@@ -1850,8 +1850,11 @@ static int get_schedule_cmd(const char *cmd, int *is_available, char **out)
 	struct string_list_item *item;
 	struct string_list list = STRING_LIST_INIT_NODUP;
 
-	if (!testing)
+	if (!testing) {
+		if (out)
+			*out = xstrdup(cmd);
 		return 0;
+	}
 
 	if (is_available)
 		*is_available = 0;

t/t7900-maintenance.sh

@@ -646,6 +646,22 @@ test_expect_success !MINGW 'register and unregister with regex metacharacters' '
 		maintenance.repo "$(pwd)/$META"
 '
 
+test_expect_success 'start without GIT_TEST_MAINT_SCHEDULER' '
+	test_when_finished "rm -rf systemctl.log script repo" &&
+	mkdir script &&
+	write_script script/systemctl <<-\EOF &&
+	echo "$*" >>../systemctl.log
+	EOF
+	git init repo &&
+	(
+		cd repo &&
+		sane_unset GIT_TEST_MAINT_SCHEDULER &&
+		PATH="$PWD/../script:$PATH" git maintenance start --scheduler=systemd
+	) &&
+	test_grep -- "--user list-timers" systemctl.log &&
+	test_grep -- "enable --now git-maintenance@" systemctl.log
+'
+
 test_expect_success 'start --scheduler=<scheduler>' '
 	test_expect_code 129 git maintenance start --scheduler=foo 2>err &&
 	test_grep "unrecognized --scheduler argument" err &&