evolve: do not exit 1 when there are no troubled changesets (issue5823) There are possibly other cases we also do not wish to exit non-zero for in this function, but I did not analyze them closely and am just looking at resolving issue5823.

# name space package to host third party extensions
from __future__ import absolute_import
import pkgutil
__path__ = pkgutil.extend_path(__path__, __name__)