I don't like this. If we're going to fall back on a default it shouldn't be part of the form. It should be part of the views.

On that note, don't we already have it?
https://github.com/AdrianGaudebert/socorro-crashstats/blob/6cca935cd58b0a69e515bd8abf12434aae212fc3/crashstats/crashstats/views.py#L1170