convertbookmark: properly convert stacked bookmarks We ignores pure descendant when looking for revision to convert. This adds support for cases were a linear stack contains multiple bookmark (or un-bookmarked descendants exists). In this case, some changeset are left orphan, but we'll consider the issue as minor for now.

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