Warden::OAuth.access_token_user_finder doesn't work well with multiple devise scopes

In my application I have 2 different devise scopes.  When using devise-twitter to do the perform_connect, upon the invocation of Warden::OAuth.access_token_user_finder, the block is using @env['warden'].user to retrieve the currently logged in user which when using multiple scope is nil.  Replacing that with @env['warden'].user(@scope) fixes this issue.
