[notmuch] Mail in git

[Ben Gamari]

Excerpts from Mark Anderson's message of Wed Feb 17 14:23:48 -0500 2010:
> But if we have notmuch as a cache of the tags, then don't we already
> know the tree objects that need updating?  Yes, we would probably need
> some consistency checks for when things don't work as planned, but in
> the common case we ought to always know.
> 
Cached or not, rewriting would still be an incredibly (e.g.
prohibitively or close to it) expensive operation for a large mailstore.

> Perhaps I'm misunderstanding these tree objects, and you're suggesting
> that we don't even tell notmuch about them.
> 
I think it would be unwise to teach notmuch anything about the
underlying store. That would be leaking way too many implementation
details into 

- Ben