Pierre-Yves David <pierre-yves.david@logilab.fr> [Mon, 30 Jan 2012 17:33:09 +0100] rev 16025
phases: write default phase data as soon as possible.
Marks phase data as dirty when computing default phase. Actual writing is done
when the lock is released. So, read only operation don't write phase data
because they don't lock the repo.