compat: fix stablerange for mercurial 3.9 Lrudict.get change of api between mercurial 3.9 and mercurial 4.2. Bypass this limitation by using lrudict.__getitem__ and catch the KeyError directly.

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