evolve: fix the dirstate after setting parents with dirty wdir (issue5930) Before this patch, during an interrupted evolve it can be confused about copies. This patch fix the dirstate when parents are changed using dirstate.setparents() with a dirty wdir. Changes in test file reflect the fixed behaviour.

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