Fix front-end for branches that happen to contain urlencoding escape characters (e.g. %).
Adding a branch with a name like "foo%20bar" (via command-line) and setting it to the project's default branch causes the project "show" page to 404 for that project. "assign_ref_vars" unescapes the branch name ("foo%20bar" ==> "foo bar"), making GitLab look for a non-existent branch.
This MR adds logic to skip the URL unescaping step in "assign_ref_vars".