tests/notcapable

ui: add support for a tweakdefaults knob

We've been talking for years about a one-stop config knob to opt in to
better behavior. There have been a lot of ideas thrown around, but
they all seem to be too complicated to get anyone to actually do the
work.. As such, this patch is the stupidest thing that can possibly
work in the name of getting a good feature to users.

Right now it's just three config settings that I think are generally
uncontroversial, but I expect to add more soon. That will likely
include adding new config knobs for the express purpose of adding them
to tweakdefaults.

# Disable the $CAP wire protocol capability.

if test -z "$CAP"
then
    echo "CAP environment variable not set."
fi

cat > notcapable-$CAP.py << EOF
from mercurial import extensions, peer, localrepo
def extsetup():
    extensions.wrapfunction(peer.peerrepository, 'capable', wrapcapable)
    extensions.wrapfunction(localrepo.localrepository, 'peer', wrappeer)
def wrapcapable(orig, self, name, *args, **kwargs):
    if name in '$CAP'.split(' '):
        return False
    return orig(self, name, *args, **kwargs)
def wrappeer(orig, self):
    # Since we're disabling some newer features, we need to make sure local
    # repos add in the legacy features again.
    return localrepo.locallegacypeer(self)
EOF

echo '[extensions]' >> $HGRCPATH
echo "notcapable-$CAP = `pwd`/notcapable-$CAP.py" >> $HGRCPATH