tests/test-dirstate-race.t

hg: perform update after pulling during clone with share (issue5103)

This is a graft of 60adda1a0188 and a4692267bc2d from the default
branch. Combined, they address a bug with pooled shared storage where
an update may not update to the most recent revision when performing
a `hg clone`.

The patches should have been written against the stable branch in
the beginning. I screwed up.

  $ 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