Found that devise was running slowly through unit tests due to bcrypt stretches. Bernard Schaefer purposed a less than ideal solution (http://oinopa.com/2011/02/05/want-a-faster-test-suite.html) and I found that modifying streches in the config was sufficient to reduce test cost (http://www.thepursuitofquality.com/post/66/speeding-up-devise-tests.html).
I'm still fairly new to ruby/rails so excuse an error in my solution - as well my quick scan didn't find any unit tests for this case, but I'd gladly write them if someone pointed me to the file required.
Added conditional to reduce test cost.
I wouldn't like to ship that code in devise itself. Why? Devise is used a lot by people starting with Rails and that would cause confusion and potential misuse. Thanks for the pull request!