evolve: prompt user to select destination for stabilization in case of split This patch adds functionality to prompt user to select a revision when there exists multiple stabilization destination because of split on multiple branches. Test are also added for the feature. I am not sure whether this is the best message which we can show, if people have suggestions I will like to improve the messages shown in prompt.

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