I screw up git release/unstable

[Graham Percival]

We had three people working on build stuff this morning, and in the
mix I decided to use different version numbers when adding \version
"2.12.0" to files.  release/unstable is a mess.

Could somebody make release/unstable be exactly the same as master?  I
don't care if you delete it and make a new one, or do some fancy git
thing to move the ref around, or what... I just want to get rid of all
current differences between master and release/unstable, without doing
anything to master.  The only "good" change that we'd lose would be
the news item, but that was just an exact copy of the previous 10
release announcements, so no worries.

I'm too frazzled about getting my project finished before RMLL to play
more games with git.

Cheers,
- Graham