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.

import sys

for line in sys.stdin:
    if line.lower() in ("message-id: \n", "in-reply-to: \n"):
        line = line[:-2]
    print(line, end="")