intridea/omniauth-identity — pull request #47 by ghiblin (2013-01-22 16:36:45+00:00)
Title: Update lib/omniauth/identity/secure_password.rb

I'm working in a scenario where I use my User model insted of Identity, and I have a guest user that does not need a password, so, when I set a nil password to it, I get an "undefined method 'empty?' for nil:NilClass" error message.
This fix it.