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.
#require test-repo pyflakes
Copied from Mercurial core (60ee2593a270)
$ cd "`dirname "$TESTDIR"`"
run pyflakes on all tracked files ending in .py or without a file ending
(skipping binary file random-seed)
$ hg locate 'set:(**.py or grep("^#!.*python")) - removed()' 2>/dev/null \
> | xargs pyflakes 2>/dev/null