commitextras: work nicely with other extensions Before this change, it doesn't add these extra fields when loaded alongside another extension that does a bunch of things, including wrapping commit. I did not investigate exactly why, but - the documentation of extensions.wrapfunction says to use subclassing to play nicely with other extensions - using subclassing does make commitextras work when loaded alongside my other extension Differential Revision: https://phab.mercurial-scm.org/D4404