[notmuch] nested tag trees (was: Mail in git)

[Ben Gamari]

Excerpts from Michal Sojka's message of Fri Feb 19 04:52:18 -0500 2010:
> Why do you want to store tag-to-message mapping in git? This is IMHO
> perfectly solved by Xapian so storing message-to-tag mapping would be
> sufficient, wouldn't it?
> 
In my case, I would like to keep the entire state of my mail store
synchronized between multiple machines. This includes both messages and
metadata alike. It seems clear that Xapian would still be necessary for
querying in reaonable time, but I feel like tag storage itself should
have support beyond just the indexer.

- Ben