Corrected app_loading test so it does not generate a key error when TZ is not set in the environment (e.g., on Windows).
Corrected app_loading test so it does not generate a key error when TZ is not set in the environment (e.g., on Windows).

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extra : convert_revision : svn%3Abcc190cf-cafb-0310-a4f2-bffc1f526a37/django/trunk%4012379

Belgabor/django,Belgabor/django,Belgabor/django