evolve: remove not required calls to phases.retractboundary() To make sure phases are preserved during evolve, we started using the phases.new-commit config option. Now we don't need to call phases.retractboundary(). Let's remove the redundant code.

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