andymckay/zamboni — comment on commit 08b5ac9b4bd5c1de1775964d40a9bc7849764d6c
File: apps/market/models.py line 191
By andymckay:

it's nullable because i hope we get more payment providers than paypal, eg stripe and it won't be required that you'll have them all. Plus I was thinking people should be able to wipe their keys. I felt it would be better to keep an empty row around than delete it.