- dont do anything if he doesn't even have read access
- move the GL_USER check to the right place! (to when you actually
will be doing something)
That spurious check for GL_USER that we (re)moved would not only have
shown an incomplete set of log lines, it would have made the wrong log
line look like the "last" one. (No real harm would result, of course,
since the update-ref would blow up due to the actual SHA being something
other than what it was expecting, but it would be confusing to the user)
