pyoxidized: add a copy of the `contrib` directory in the right location
This get the hacky setup closer to how an actual install is setup.
Differential Revision: https://phab.mercurial-scm.org/D11291
{
"conduit_uri": "https://phab.mercurial-scm.org/api",
"phabricator.uri": "https://phab.mercurial-scm.org/",
"repository.callsign": "HG",
"arc.land.onto.default": "@",
"base": "hg:.^"
}