fold: replace a compat condition with a less specific proxy
If `scmutil.cleanupnodes()` is overridden, the check in
`scmutil.cleanupnodes.__code__.co_varnames` will fail. Let's use a
less specific proxy for that condition so extensions are safely
override `scmutil.cleanupnodes()`. I picked `util.safehasattr(scmutil,
'nullrev')` as the proxy. That basically checks for Mercurial commit
d739f423bf06, which is two commits later than the commit we actually
care about.
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/