phases: avoid a potentially costly dictionary interation in some case If we retract for the draft phase, there is not non-public item to be retracted and we can skip this part. This part is was apparently super costly thanks to Python. On mozilla-try-2019-02-18, a perf::unbundle call with a 10 000 changesets bundle gives give use the following timing. e57d4b868a3e: 4.6 seconds ac1c75188440: 102.5 seconds this-changeset: 30.0 seconds So we recovered about ⅔ of the regression, the next changeset will give us the rest back.

Set up

  $ hg init repo
  $ cd repo
  $ echo a > a
  $ hg add a
  $ hg commit -m a

Try to import an empty patch

  $ hg import --no-commit - <<EOF
  > EOF
  applying patch from stdin
  abort: stdin: no diffs found
  [10]

No dirstate backups are left behind

  $ ls .hg/dirstate* | sort
  .hg/dirstate