There are some variations in the printed names of exceptions between Oracle and

other database backends, but the exception classes should still be the same.
This commit changes the way the tests check for specific database errors to be
more portable between implementations.

It's possible these tests will still fail if, e.g., Oracle doesn't raise
IntegrityError (but raises DatabaseError) when we except it to, but we can
cross that bridge if and when it appears.


git-svn-id: http://code.djangoproject.com/svn/django/trunk@8450 bcc190cf-cafb-0310-a4f2-bffc1f526a37