The first reason is that we don't want to force the user to use the ``--git_protocol`` option, if possible we would like to just do the right thing. So as Peter mentioned initially we assumed that if you had checked out the parent project with e.g. ``https://`` then most likely you would also like to use that protocol for the rest. E.g. I default use ``git@`` on my machines since I have my key chain here setup so that I don't have to put in any passwords. However, Peter on the other hand uses ``https://``.