Django should call time.tzset after setting TZ environment variable.

[Marc Fargas <telenieko@…>]

After reading #2315 I spoted this on python's documentation:

  Note: Although in many cases, changing the TZ environment variable may affect
  the output of functions like localtime without calling tzset, this behavior should not be relied on.
  The TZ environment variable should contain no whitespace. 

So, Django should call tzset after setting the TZ environment variable!

Origin: ​http://docs.python.org/lib/module-time.html

[Matt Boersma]

One-liner that fixes #3350.

[Malcolm Tredinnick]

(In [6300]) Fixed #3350 -- Fixed timezone setting. Thanks, Matt Boersma.