test: use `hg debugrequires` instead of `cat` in some tests This give the "same" result, while taking in account that the requirement file might be in different location, like what `share-safe` is doing. Differential Revision: https://phab.mercurial-scm.org/D11895

# name space package to host third party extensions
from __future__ import absolute_import
import pkgutil

__path__ = pkgutil.extend_path(__path__, __name__)