Quote the branch name in "Check out branch" button

In https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/22056 the branch name is #51457-Show-percentage-of-language-detection-on-the-language-bar thus it's showing this command:

git fetch git@gitlab.com:johann.sonntagbauer/gitlab-ce.git #51457-Show-percentage-of-language-detection-on-the-language-bar
git checkout -b johann.sonntagbauer/gitlab-ce-#51457-Show-percentage-of-language-detection-on-the-language-bar FETCH_HEAD

However see that the branch name becomes a comment? So it won't work if we just copy and paste in the terminal.

Actual screenshot:

We'll need to quote the branch name, or escape special character like that. Note that a branch could be tmp'" so this quote can't be dumb.