tests/test-absorb-phase.t

dirstate: explicitly write the dirstate after `keyword` "overwrite"

I am working on making the dirstate write patterns more predictable. This patch is
part of a small series of similar patches that adds a explicit dirstate write in
a handful of location where the dirstate is updated "a bit in a strange way".

With this explicit write, we are no longer relying on implicite write of the
dirstate on `wlock` release. This make the world a better place.

  $ cat >> $HGRCPATH << EOF
  > [extensions]
  > absorb=
  > drawdag=$TESTDIR/drawdag.py
  > EOF

  $ hg init
  $ hg debugdrawdag <<'EOS'
  > C
  > |
  > B
  > |
  > A
  > EOS

  $ hg phase -r A --public -q
  $ hg phase -r C --secret --force -q

  $ hg update C -q
  $ printf B1 > B

  $ hg absorb -aq

  $ hg log -G -T '{desc} {phase}'
  @  C secret
  |
  o  B draft
  |
  o  A public