tests/test-dirstate-race.t

destroyed: keep the filecache in sync with __dict__ (issue3335) (issue3693) (issue3743)

We need to make sure that if X is in the filecache then it's also in the
filecache owner's __dict__, otherwise it will go out of sync:

repo.X                  # first access to X, records stat info in
                        # filecache and updates __dict__
repo._filecache.clear() # removes X from _filecache but it's still in __dict__
repo.invalidate()       # iterates over _filecache and removes entries
                        # from __dict__, but X isn't in _filecache, so
                        # it's kept in __dict__
repo.X                  # X is fetched from __dict__, bypassing the filecache

  $ hg init
  $ echo a > a
  $ hg add a
  $ hg commit -m test

Do we ever miss a sub-second change?:

  $ for i in 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20; do
  >     hg co -qC 0
  >     echo b > a
  >     hg st
  > done
  M a
  M a
  M a
  M a
  M a
  M a
  M a
  M a
  M a
  M a
  M a
  M a
  M a
  M a
  M a
  M a
  M a
  M a
  M a
  M a