rewind: make sure merge commits include files from p1 and p2 Otherwise rewinding a merge commit makes it lose all changes. This fix populates `updates` argument of rewriteutil.rewrite() with parent changesets. That argument is normally used for folding multiple changesets, but in this case it's simply used to include files from p1 and p2. Usually, rewrite() works fine using ctx.files(), but that function can return an empty list when ctx is a merge commit.

#require test-repo

  $ checkflake8() {
  >   if ! (which flake8 > /dev/null); then
  >     echo skipped: missing tool: flake8;
  >     exit 80;
  >   fi;
  > };
  $ checkflake8

Copied from Mercurial core (60ee2593a270)

  $ cd "`dirname "$TESTDIR"`"

run flake8 if it exists; if it doesn't, then just skip

  $ hg files -0 'set:(**.py or grep("^#!.*python")) - removed()' \
  > -X hgext3rd/evolve/thirdparty \
  > 2>/dev/null \
  > | xargs -0 flake8