remote.c: reject 0-length branch names

Branch names can't be empty, so config keys with an empty branch name,
e.g. "branch..remote", are silently ignored.

Since these config keys will never be useful, make it a fatal error when
remote.c finds a key that starts with "branch." and has an empty
subsection.

Signed-off-by: Glen Choo <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: chooglen

remote.c

@@ -352,8 +352,12 @@ static int handle_config(const char *key, const char *value, void *cb)
 	struct remote_state *remote_state = cb;
 
 	if (parse_config_key(key, "branch", &name, &namelen, &subkey) >= 0) {
+		/* There is no subsection. */
 		if (!name)
 			return 0;
+		/* There is a subsection, but it is empty. */
+		if (!namelen)
+			return -1;
 		branch = make_branch(remote_state, name, namelen);
 		if (!strcmp(subkey, "remote")) {
 			return git_config_string(&branch->remote_name, key, value);

t/t5516-fetch-push.sh

@@ -602,13 +602,23 @@ test_expect_success 'branch.*.pushremote config order is irrelevant' '
 	check_push_result two_repo $the_commit heads/main
 '
 
-test_expect_success 'push ignores empty branch name entries' '
+test_expect_success 'push rejects empty branch name entries' '
 	mk_test one_repo heads/main &&
 	test_config remote.one.url one_repo &&
 	test_config branch..remote one &&
 	test_config branch..merge refs/heads/ &&
 	test_config branch.main.remote one &&
 	test_config branch.main.merge refs/heads/main &&
+	test_must_fail git push 2>err &&
+	grep "bad config variable .branch\.\." err
+'
+
+test_expect_success 'push ignores "branch." config without subsection' '
+	mk_test one_repo heads/main &&
+	test_config remote.one.url one_repo &&
+	test_config branch.autoSetupMerge true &&
+	test_config branch.main.remote one &&
+	test_config branch.main.merge refs/heads/main &&
 	git push
 '