A second push is not creating a new branch

Closes https://gitlab.com/gitlab-org/gitlab-qa/issues/246

qa/qa/factory/resource/merge_request.rb

@@ -32,6 +32,7 @@ module QA
           push.project = factory.project
           push.branch_name = factory.target_branch
           push.remote_branch = factory.source_branch
+          push.new_branch = false
           push.file_name = "added_file.txt"
           push.file_content = "File Added"
         end