cmd_config(): make a copy of path obtained from git_path()

The strings returned by git_path() are recycled after a while.  Make
a copy of the config filename rather than holding onto the return
value from git_path().

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/config.c

@@ -568,8 +568,8 @@ int cmd_config(int argc, const char **argv, const char *prefix)
 		}
 	}
 	else if (actions == ACTION_EDIT) {
-		const char *config_file = given_config_source.file ?
-			given_config_source.file : git_path("config");
+		char *config_file;
+
 		check_argc(argc, 0, 0);
 		if (!given_config_source.file && nongit)
 			die("not in a git directory");
@@ -578,6 +578,8 @@ int cmd_config(int argc, const char **argv, const char *prefix)
 		if (given_config_source.blob)
 			die("editing blobs is not supported");
 		git_config(git_default_config, NULL);
+		config_file = xstrdup(given_config_source.file ?
+				      given_config_source.file : git_path("config"));
 		if (use_global_config) {
 			int fd = open(config_file, O_CREAT | O_EXCL | O_WRONLY, 0666);
 			if (fd) {
@@ -590,6 +592,7 @@ int cmd_config(int argc, const char **argv, const char *prefix)
 				die_errno(_("cannot create configuration file %s"), config_file);
 		}
 		launch_editor(config_file, NULL, NULL);
+		free(config_file);
 	}
 	else if (actions == ACTION_SET) {
 		int ret;