evolve: check for None before adding in set of revisions to strip After previous patch, replacements can contain None. Let's make sure we don't add None to the revisions to strip during `hg evolve --abort` The test changes demonstrate the usefulness of this and the previous patch. Now abort is working and public changesets are not a problem.

#require test-repo pyflakes

Copied from Mercurial core (60ee2593a270)

  $ cd "`dirname "$TESTDIR"`"

run pyflakes on all tracked files ending in .py or without a file ending
(skipping binary file random-seed)

  $ hg locate 'set:(**.py or grep("^#!.*python")) - removed()' 2>/dev/null \
  > | xargs pyflakes 2>/dev/null