obslog: uniformize `_debugobshistoryrevs` and `_debugobshistorygraph` arguments `_debugobshistoryrevs` and `_debugobshistorygraph` perform quite the same action, the latter simply add graph support. Consequently, it looks better for them to have the same argument list.

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