We used to unconditionally set the title of the branch
to the current branch. This worked fine in most cases
where the current branch was already known, but failed
when you use 'gitx -c' and then switch to the HistoryView,
because then the currentBranch isn't known yet.
The simple fix is to check if we know it. If we don't,
it'll be set later on.
This wasn't used anyway. A good idea would be to create a new
branchcontroller that takes care of all these revs, rather than
letting PBGitRepository take care of that
That's why it's there, after all. This also makes the system
more robust and catches some more errors.
The next thing this enables is to also allow right-clicking
on refs in the commit list.
The ref functionality is somewhat weird right now, in that
some parts of the code require a nil array when there are no
refs. So, we add a good removeRef accessor to keep track of this