No subject

fixes a test case I'm working on for the bfiles extension (which uses
its own private dirstate) so it behaves deterministically.  But the
documentation is a bit scant.  Adrian posted a patch back in May
(http://www.selenic.com/pipermail/mercurial-devel/2009-May/012594.html)
that would improve the matter, but it's still not entirely clear to
me.

So... what is the purpose of dirstate.granularity?  When would you set
it, what would you set it to, and why?  Is setting it to 0 to
workaround a racy-looking test case appropriate?

Thanks --

Greg