Avoid MoreThanOne Error (#19557) (#19591)

Backport #19557

Author: 99rgosse

services/repository/branch.go

@@ -35,7 +35,7 @@ func CreateNewBranch(doer *user_model.User, repo *repo_model.Repository, oldBran
 
 	if err := git.Push(git.DefaultContext, repo.RepoPath(), git.PushOptions{
 		Remote: repo.RepoPath(),
-		Branch: fmt.Sprintf("%s:%s%s", oldBranchName, git.BranchPrefix, branchName),
+		Branch: fmt.Sprintf("%s%s:%s%s", git.BranchPrefix, oldBranchName, git.BranchPrefix, branchName),
 		Env:    models.PushingEnvironment(doer, repo),
 	}); err != nil {
 		if git.IsErrPushOutOfDate(err) || git.IsErrPushRejected(err) {