tests/test-dirstate-version-fallback.t

phases: directly update the phase sets in advanceboundary

This is similar to what we do in retractboundary. There is no need to invalidate
the cache if we have everything at hand to update it.

  $ cat >> $HGRCPATH << EOF
  > [storage]
  > dirstate-v2.slow-path=allow
  > [format]
  > use-dirstate-v2=no
  > EOF

Set up a v1 repo

  $ hg init repo
  $ cd repo
  $ echo a > a
  $ touch file-with-somewhat-long-name-to-make-dirstate-v1-bigger-than-v2
  $ hg commit -Aqm a
  $ hg debugrequires | grep dirstate
  [1]
  $ ls -1 .hg/dirstate*
  .hg/dirstate

Copy v1 dirstate
  $ cp .hg/dirstate $TESTTMP/dirstate-v1-backup

Upgrade it to v2

  $ hg debugupgraderepo -q --config format.use-dirstate-v2=1 --run | grep -E 'added:|removed:'
     added: dirstate-v2
  $ hg debugrequires | grep dirstate
  dirstate-v2
  $ ls -1 .hg/dirstate*
  .hg/dirstate
  .hg/dirstate.* (glob)

Manually reset to dirstate v1 to simulate an incomplete dirstate-v2 upgrade

  $ rm .hg/dirstate*
  $ cp $TESTTMP/dirstate-v1-backup .hg/dirstate

There should be no errors, but a v2 dirstate should be written back to disk
  $ hg st
  $ ls -1 .hg/dirstate*
  .hg/dirstate
  .hg/dirstate.* (glob)

Corrupt the dirstate to see how the errors show up to the user
  $ echo "I ate your data" > .hg/dirstate

  $ hg st
  abort: working directory state appears damaged! (no-rhg !)
  (falling back to dirstate-v1 from v2 also failed) (no-rhg !)
  abort: Too little data for dirstate: 16 bytes. (rhg !)
  [255]