[1.2.X] Implemented changes made in r14320 in the Oracle backend. Thanks...

[1.2.X] Implemented changes made in r14320 in the Oracle backend. Thanks Russell for reviewing the proposed fix.

Backport of [14510] from trunk

git-svn-id: http://code.djangoproject.com/svn/django/branches/releases/1.2.X@14511 bcc190cf-cafb-0310-a4f2-bffc1f526a37