I'm not sure if the mark-up has addressed my concern.  My worry is that we might (for some reason) build from `https://github.com/Metaswitch/sprout.git` rather than `git@github.com:Metaswitch/sprout.git`.  If we do, this sed expression doesn't give the right answer.

    # echo https://github.com/Metaswitch/sprout.git | sed -e 's#^\([^:]*\):\([^/]*\)\([^.]*\)[.]git#http://\1/\2\3/tree/#'
    https://github.com/Metaswitch/sprout.git

It might be OK just to block people from building from `https://github.com/Metaswitch/sprout.git` but I think we should do so explicitly - it's easy to do by accident (e.g. if you take the git URL from github when not logged in).