volunteers for commit-finding for a regression

[Graham Percival]

We've found a regression; I'll announce that the release candidate
is no good.  Here's the issue:
http://code.google.com/p/lilypond/issues/detail?id=1472

Do we have any volunteers to find the exact commit in which this
broke?  Recently-rewritten instructions here:
http://lilypond.org/doc/v2.13/Documentation/contributor/finding-the-cause-of-a-regression

- you need a fairly fast computer
- you'll probably need to recompile lilypond (not from scratch)
  about 30 times
- it doesn't need a lot of thought; it's definitely doable while
  you're working on other stuff, or cooking dinner, or whatever.

If there's no takers, I can definitely do it tomorrow.  But it's
an easy task for a non-programmer to do, and if somebody else
tackles this, I'll spend my time writing the release notes
instead.

Cheers,
- Graham