[1.2.X] Fixed #15067 -- Modified the range checks on base36_to_int so you are...

[1.2.X] Fixed #15067 -- Modified the range checks on base36_to_int so you are guaranteed to always get an int, avoiding possible OverflowErrors. Thanks to Garthex for the report, jboutros for the patch, and kfrazier for the feedback.

Backport of r15288 from trunk.

git-svn-id: http://code.djangoproject.com/svn/django/branches/releases/1.2.X@15289 bcc190cf-cafb-0310-a4f2-bffc1f526a37