topics: take locks and start transaction before calling _changetopics This will help us in calling _changetopics in other transactions which already started. Currently the _changetopics creates its own transaction and hence can't be used it a same transaction with any other function or logic.

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