compat: fix obslog compatiblity with 4.3
Due to the way of how successor sets are retrieved in new Mercurial version,
retrieving it again in 4.3 way would be a performance hit and complexify the
code too much.
Don't retrieve markers of successor sets which makes obslog filtered output
more limited in 4.3.
syntax: re
/figures/[^/]+\.png$
^html/
\.pyc$
~$
\.swp$
\.orig$
\.rej$
^tests/.*\.err$
^tests/easy_run.sh$
^build/
^dist/
^MANIFEST$
^docs/tutorials/.*\.rst$
\.ico$
tests/\.testtimes
^docs/training/graphs/
^docs/training/html/
^docs/training/index.html
^docs/training/graphviz-images/
^docs/training/img/
^docs/training/output/
^docs/training/pandocfilters/