hg: allow usage of XDG_CONFIG_HOME/hg/hgrc
Modern applications must use the following paths to store configuration files:
- $XDG_CONFIG_HOME/hg/hgrc,
- $HOME/.config/hg/hgrc (if XDG_CONFIG_HOME is unset or not absolute).
For backward compatibility, ~/.hgrc is still created if no hgrc exist using hg
config --edit.
See https://standards.freedesktop.org/basedir-spec/basedir-spec-latest.html
Our full contribution guidelines are in our wiki, please see:
https://www.mercurial-scm.org/wiki/ContributingChanges
If you just want a checklist to follow, you can go straight to
https://www.mercurial-scm.org/wiki/ContributingChanges#Submission_checklist
If you can't run the entire testsuite for some reason (it can be
difficult on Windows), please at least run `contrib/check-code.py` on
any files you've modified and run `python contrib/check-commit` on any
commits you've made (for example, `python contrib/check-commit
273ce12ad8f1` will report some style violations on a very old commit).