Fix recursion issues in the session db backend.
Fix recursion issues in the session db backend.

Patch submitted by Bernd Dorn of Lovely Systems. Fixes issue #87.


git-svn-id: 7c59d995a3d63779dc3f8cdf6830411bfeeaa67b@61 d4307497-c249-0410-99bd-594fbd7e173e

clones/google-app-engine-django,wtanaka/google-app-engine-helper-for-django