evolve: always create commit when resolving divergence When resolving content-divergence, the final commit we create may end up empty (which means that Mercurial won't even create it). We've had code for handling that in evolve ever since 41bf6c27a122 (evolve: stabilize now handle conflicting changeset, 2012-08-23). However, that resolved the issue by marking on the divergent commits as successor. As Pierre-Yves has pointed out (in other code reviews), we should instead be creating a new successor. So that's what this patch does. It does that by setting `ui.allowemptycommit` while creating the final commit. However, that is not enough, because we may end up creating the same nodeid as already existed (we'd then end up trying to mark the "new" commit a successor of itself). To solve that, we add some salt to the commit extras. That salt affects lots of tests.

#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