effectflag: fix content change detection for filtered revs In some cases (like amended an obsolete changeset), computing the diff and comparing them need to work with filtered revisions. We need to use unfiltered change contexts to safely compute diffs.

syntax: re
/figures/[^/]+\.png$
^html/
\.pyc$
~$
\.swp$
\.orig$
\.rej$
\.err$
^tests/easy_run.sh$
^build/
^dist/
^MANIFEST$
^docs/tutorials/.*\.rst$
\.ico$
tests/\.testtimes