thirdparty: don't make zope a namespace package There are a gazillion zope.* packages in the wild. So zope/__init__.py needs to be a namespace package. But in Mercurial, we have 1 zope package. And even if we had multiple packages, they'd all be in thirdparty/zope/. So we don't need a namespace package. Differential Revision: https://phab.mercurial-scm.org/D2929