Use hashlib if running under Python 2.5

[Rob Hudson <treborhudson@…>]

This was discussed here:
​http://groups.google.com/group/django-developers/browse_thread/thread/d5f0951f47889770/4cb8257b8d4d8c28

Python 2.5 has deprecated the use of the sha1 and md5 modules in favor of the hashlib module. A patch will be following that implements django.contrib.auth.models methods using hashlib.

[Fredrik Lundh <fredrik@…>]

Possible change: instead of doing

    try:
        # Python 2.5 has moved to using hashlib for hashing functions
        import hashlib
        ... use hashlib
    except ImportError:
        ... use old libraries

do

    try:
        # Python 2.5 has moved to using hashlib for hashing functions
        import hashlib
    except ImportError:
        # Fallback
        ... use old libraries ...
    else:
        ... use hashlib ...

Also, this test lacks explicit tests, but I think the functionality should be covered by other existing tests.

[Adrian Holovaty]

I'm working on checking this in.

[Adrian Holovaty]

(In [6318]) Fixed #3604 -- django.contrib.auth password checking now uses hashlib if it's available. Thanks, Rob Hudson