prune: use action "prune", not "touch", in precheck
We have been using "touch" since 06ee4ec88190 (prune: use precheck to
validate revision, 2017-07-23). That commit modified the tests, so it
kind seemed intentional, but I suspect it was still just an oversight.
# name space package to host third party extensions
from __future__ import absolute_import
import pkgutil
__path__ = pkgutil.extend_path(__path__, __name__)