The Hosting adapter causes multiple calls to be sent to 'entries' on
the git_adapter(repositories_controller_path#show_with_git_instructions
adds a second (non vanilla chiliproject) call.

As this method is very expensive, this has a performance impact we can
avoid!

It might be better to provide a dedicated method to the patched
git_adapter to determine whether a repository is 'empty' or not
rather than having to fetch the entries, but this will work for now.

There is some logic in update_repositories to avoid 'recursion'
however this does not protect against the case where an
observed change leads to multiple calls to update_repositories
for the same project (or projects.)

An example change that could cause this is is to add a *group*
with commit rights as a project's member.  The update_repositories
method will then get called for both the group's addition and
each subsequent member of that group.  This change avoids those
un-neccessary secondary calls.