branches: fix error message for invalid name

Author: yuangli

src/branch.c

@@ -54,6 +54,12 @@ static int not_a_local_branch(const char *reference_name)
 
 static bool branch_name_follows_pattern(const char *branch_name)
 {
+	/*
+	 * Discourage branch name starting with dash,
+	 * https://github.com/git/git/commit/6348624010888b
+	 * and discourage HEAD as branch name,
+	 * https://github.com/git/git/commit/a625b092cc5994
+	 */
 	return branch_name[0] != '-' && git__strcmp(branch_name, "HEAD");
 }
 
@@ -78,7 +84,7 @@ static int create_branch(
 	GIT_ASSERT_ARG(git_commit_owner(commit) == repository);
 
 	if (!branch_name_follows_pattern(branch_name)) {
-		git_error_set(GIT_ERROR_REFERENCE, "'HEAD' is not a valid branch name");
+		git_error_set(GIT_ERROR_REFERENCE, "'%s' is not a valid branch name", branch_name);
 		error = -1;
 		goto cleanup;
 	}
@@ -761,12 +767,6 @@ int git_branch_name_is_valid(int *valid, const char *name)
 
 	*valid = 0;
 
-	/*
-	 * Discourage branch name starting with dash,
-	 * https://github.com/git/git/commit/6348624010888b
-	 * and discourage HEAD as branch name,
-	 * https://github.com/git/git/commit/a625b092cc5994
-	 */
 	if (!name || !branch_name_follows_pattern(name))
 		goto done;