Fixed #13140 -- Ensure that request headers are preserved through redirect...

Fixed #13140 -- Ensure that request headers are preserved through redirect chains in the test client. Thanks to David Novakovic for the report.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@13620 bcc190cf-cafb-0310-a4f2-bffc1f526a37