packaging: follow hg's supported python version (>= 2.7)
"Mercurial 4.3 and newer require Python 2.7." (From
https://www.mercurial-scm.org/wiki/SupportedPythonVersions)
Also add X- prefix, because that's the correct form, apparently.
This line can also be removed in future, since "When Debian supported multiple
Python versions, X-Python-Version was used, but it is obsolete now as no
supported Debian release supports anything other than python2.7." (From
https://wiki.debian.org/Python/LibraryStyleGuide)
That page also mentions "X-Python3-Version".
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/