obsfate: improve prune support in _successorsetverb In the prune case, still have markers (at least the prune markers). If we want to be able to return these markers we need the underlying function to support it.

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