Alright, I think I have this figured out now. You *have to* use the https
protocol, but then it should work.

   https://bitbucket.org/philexander/context-highlight.git

You cannot use any git protocol except (anonymous) https. If you try
any other protocol, the 'git clone' command that is started by the webserver
will attempt to do an interactive input query and subsequently fail.

I have updated help.html with the above explanation as well.

Best wishes,
Taco