rust-status: save new dircache even if just invalidated There was a functional race between invalidating the cache (not acted upon until the end of the status algorithm) and populating the new cache (which relies upon an up-to-date version of the cache). We simply inform the cache populating function that we've just invalidated the cache for this particular directory since the information is present in the same scope.

rust-status: fix typos and add docstrings to dircache related fields

rhg: show a bug where repeated [hg status] is needed to cache everything

upgrade: no longer keep all revlogs in memory at any point Keeping all object open is unsustainable, so we will open them on demand. This mean opening them multiple times, but this is a lesser evil. Each revlog consume a small amount of memory (index content, associated nodemap, etc). While there are few "big" revlog, the sheer amount of small filelog can become a significant issue memory wise, consuming multiple GB of memory. If you combines this extra usage with the use of multiprocessing, this usage can quickly get out of control. This can effectively block the upgrade of larger repository. This changeset fixes this issue.