wireproto: port protocol handler to zope.interface
zope.interface is superior to the abc module. Let's port to it.
As part of this, we add tests for interface conformance for
classes implementing the interface.
Differential Revision: https://phab.mercurial-scm.org/D2983
Issue351: mq: qrefresh can create extra revlog entry
$ echo "[extensions]" >> $HGRCPATH
$ echo "mq=" >> $HGRCPATH
$ hg init
$ hg qinit
$ echo b > b
$ hg ci -A -m foo
adding b
$ echo cc > b
$ hg qnew -f foo.diff
$ echo b > b
$ hg qrefresh
$ hg debugindex b
rev linkrev nodeid p1 p2
0 0 1e88685f5dde 000000000000 000000000000