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

"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))

t/t5512-ls-remote.sh

@@ -248,4 +248,13 @@ test_expect_success PIPE,JGIT,GIT_DAEMON 'indicate no refs in standards-complian
 	test_expect_code 2 git ls-remote --exit-code git://localhost:$JGIT_DAEMON_PORT/empty.git
 '
 
+test_expect_success 'ls-remote works outside repository' '
+	# It is important for this repo to be inside the nongit
+	# area, as we want a repo name that does not include
+	# slashes (because those inhibit some of our configuration
+	# lookups).
+	nongit git init --bare dst.git &&
+	nongit git ls-remote dst.git
+'
+
 test_done

t/t5550-http-fetch-dumb.sh

@@ -34,6 +34,15 @@ test_expect_success 'clone http repository' '
 	test_cmp file clone/file
 '
 
+test_expect_success 'list refs from outside any repository' '
+	cat >expect <<-EOF &&
+	$(git rev-parse master)	HEAD
+	$(git rev-parse master)	refs/heads/master
+	EOF
+	nongit git ls-remote "$HTTPD_URL/dumb/repo.git" >actual &&
+	test_cmp expect actual
+'
+
 test_expect_success 'create password-protected repository' '
 	mkdir -p "$HTTPD_DOCUMENT_ROOT_PATH/auth/dumb/" &&
 	cp -Rf "$HTTPD_DOCUMENT_ROOT_PATH/repo.git" \

transport-helper.c

@@ -124,8 +124,9 @@ static struct child_process *get_helper(struct transport *transport)
 	helper->git_cmd = 0;
 	helper->silent_exec_failure = 1;
 
-	argv_array_pushf(&helper->env_array, "%s=%s", GIT_DIR_ENVIRONMENT,
-			 get_git_dir());
+	if (have_git_dir())
+		argv_array_pushf(&helper->env_array, "%s=%s",
+				 GIT_DIR_ENVIRONMENT, get_git_dir());
 
 	code = start_command(helper);
 	if (code < 0 && errno == ENOENT)