Deal with intermittent OverflowError in gate-neutron-python26

This occurence looks like is related to a failure in
utils.execute. This patch attempts to deal with the error
by mocking out Popen.communicate altogether.

Fixes bug #1202065

Change-Id: I4092efb17939b69dd2d1965aaf619a9b2be03ef4
Fix migration branch appeared after recent commit

Fix migration branch introduced by commit that added
providernet extension support for cisco plugin

fixes bug 1205229

Change-Id: Id0f364316f19e077a388d4a343d1042a287fa96a
Merge "Deal with intermittent OverflowError in gate-neutron-python26"