Add a functional test for instance fault message with retry
Add a functional test for instance fault message with retry

This adds a functional test that simulates the last retry after a
failed driver spawn and verifies that the original exception
message is preserved/not displaced in the instance fault message
after the retries are exceeded.

Related-Bug: #1488332

Change-Id: I0c0f30598685062f321498e212a699185f925ee7

Juniper/nova,mikalstill/nova,bigswitch/nova,rahulunair/nova,Juniper/nova,jianghuaw/nova,vmturbo/nova,phenoxim/nova,openstack/nova,jianghuaw/nova,sebrandon1/nova,gooddata/openstack-nova,klmitch/nova,klmitch/nova,cloudbase/nova,Juniper/nova,rajalokan/nova,Juniper/nova,alaski/nova,jianghuaw/nova,gooddata/openstack-nova,phenoxim/nova,mikalstill/nova,cloudbase/nova,rahulunair/nova,bigswitch/nova,gooddata/openstack-nova,alaski/nova,vmturbo/nova,vmturbo/nova,rajalokan/nova,hanlind/nova,hanlind/nova,hanlind/nova,gooddata/openstack-nova,openstack/nova,openstack/nova,mahak/nova,klmitch/nova,cloudbase/nova,klmitch/nova,rajalokan/nova,sebrandon1/nova,mikalstill/nova,vmturbo/nova,rajalokan/nova,mahak/nova,mahak/nova,sebrandon1/nova,jianghuaw/nova,rahulunair/nova