Fixed #8203 -- Fixed temporary file deleation on Windows and a couple of edge

cases on Unix-like systems. Patch from snaury. Testing and verification on
Windows, Mac and Linux from cgrady and ramikassab.


git-svn-id: http://code.djangoproject.com/svn/django/trunk@8493 bcc190cf-cafb-0310-a4f2-bffc1f526a37