Use save_and_reraise_exception() in HeatException
Use save_and_reraise_exception() in HeatException

Storing sys.exc_info() in a local variable in HeatException.__init__ would
have caused a reference loop in cases where formatting the exception
message failed.

Change-Id: I29502344713e5d4da761d9277b445a6921dbd83b
Related-Bug: #1626675

noironetworks/heat,noironetworks/heat,openstack/heat,openstack/heat