Django admin 'Now' button wrong timezone

Question

I'm getting the browser time when I click the 'Now' button on the Django admin page for a DateTimeField. I did some research and it appears this was fixed in Django 1.7 (reference: http://bit.ly/1d2zqRa - I'm running 1.7.8).

Here is the model in models.py I have:

class WorkWindow(models.Model):
    start_time = models.DateTimeField()
    end_time = models.DateTimeField()

In admin.py I have:
admin.site.register(WorkWindow)

In settings.py I have:
TIME_ZONE = 'America/Los_Angeles'
USE_I18N = True
USE_L10N = True
USE_TZ = True

This appears to be exactly the same problem as what was fixed here: http://bit.ly/1GtJ8Xr. Am I missing something? Thanks in advance!