evolve: move logic to resolve phase-divergence in a new function
This patch moves logic which does the revert and create a commit on top of
public changeset because we need to repeat that logic while handling
continuation of `hg evolve` when there are conflicts while rebasing the
phase-divergent changeset.
syntax: re
/figures/[^/]+\.png$
^html/
\.pyc$
~$
\.swp$
\.orig$
\.rej$
^tests/.*\.err$
^tests/easy_run.sh$
^build/
^dist/
^MANIFEST$
^docs/tutorials/.*\.rst$
\.ico$
tests/\.testtimes
^docs/training/graphs/
^docs/training/html/
^docs/training/index.html
^docs/training/graphviz-images/
^docs/training/img/
^docs/training/output/
^docs/training/pandocfilters/