Merge branch 'km/gc-eperm' into maint

A "gc" process running as a different user should be able to stop a
new "gc" process from starting.

* km/gc-eperm:
  gc: notice gc processes run by other users

builtin/gc.c

@@ -222,7 +222,7 @@ static const char *lock_repo_for_gc(int force, pid_t* ret_pid)
 			time(NULL) - st.st_mtime <= 12 * 3600 &&
 			fscanf(fp, "%"PRIuMAX" %127c", &pid, locking_host) == 2 &&
 			/* be gentle to concurrent "gc" on remote hosts */
-			(strcmp(locking_host, my_host) || !kill(pid, 0));
+			(strcmp(locking_host, my_host) || !kill(pid, 0) || errno == EPERM);
 		if (fp != NULL)
 			fclose(fp);
 		if (should_exit) {