view CONTRIBUTING @ 30351:f81002f736d7

bundle2: use new compression engine API for compression

Now that we have a new API to define compression engines, let's put it
to use!

The new code stores a reference to the compression engine instead of
a low-level compressor object. This will allow us to more easily
transition to different APIs on the compression engine interface
once we implement them.

As part of this, we change the registration in bundletypes to use 'UN'
instead of None. Previously, util.compressors had the no-op compressor
registered under both the 'UN' and None keys. Since we're switching to
a new API, I don't see the point in carrying this dual registration
forward.

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).