Merge branch 'jn/remote-helpers-with-git-dir'

"git ls-remote" and "git archive --remote" are designed to work
without being in a directory under Git's control.  However, recent
updates revealed that we randomly look into a directory called
.git/ without actually doing necessary set-up when working in a
repository.  Stop doing so.

* jn/remote-helpers-with-git-dir:
  remote helpers: avoid blind fall-back to ".git" when setting GIT_DIR
  remote: avoid reading $GIT_DIR config in non-repo

remote.c

@@ -693,7 +693,7 @@ static struct remote *remote_get_1(const char *name,
 		name = get_default(current_branch, &name_given);
 
 	ret = make_remote(name, 0);
-	if (valid_remote_nick(name)) {
+	if (valid_remote_nick(name) && have_git_dir()) {
 		if (!valid_remote(ret))
 			read_remotes_file(ret);
 		if (!valid_remote(ret))