[MERGE] Cause 32 less test skips, take 2: cloning_metadir RPC support for branch refs

[Andrew Bennetts]

John Arbash Meinel wrote:
[...]
> > 
> > So here's the updated patch.  The test_bzrdir.py changes are the same as
> > before I think, but obvious the RPC changes are new.
[...]
> 
> So this changes the RPC, but you feel it is okay becuase it hasn't been
> in bzr.dev for very long?

That's right.

> So my primary concern is RPC compatibility, but as long as it hasn't
> "leaked into the wild" yet:
> BB:approve

Yep, I'd probably rename the RPC if the rc1 had been released.

Thanks for the review.

-Andrew.