Fixed #8315 -- If an exception is raised whilst trying to rollback a

transaction (after another exception in the code), make sure the original
exception is reported, rather than the rollback-generated one. The latter is
almost certainly a consequence of the former. Patch from Karen Tracey.


git-svn-id: http://code.djangoproject.com/svn/django/trunk@8411 bcc190cf-cafb-0310-a4f2-bffc1f526a37