[1.1.X] Fixed #12720 -- Corrected handling of cookies in the TestClient....

[1.1.X] Fixed #12720 -- Corrected handling of cookies in the TestClient. Thanks to James Henstridge for the report and patch.

Backport of r12343 from trunk.

git-svn-id: http://code.djangoproject.com/svn/django/branches/releases/1.1.X@12344 bcc190cf-cafb-0310-a4f2-bffc1f526a37