I had the same problem, it looks like a problem inside Devise (still present in master). The only solution I found was to return to Devise 2.1.2 (I knew that it worked because I used it in another project).
So, to fix this problem, you can put
gem 'devise', '2.1.2'
in your gemfile and then reinstall it using
rails generate devise:install
Hope this helps you while the development team is fixed.
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