avoids conflicts with users using email as username

app/models/user.rb

@@ -292,7 +292,8 @@ class User < ActiveRecord::Base
   def self.find_for_database_authentication(warden_conditions)
     conditions = warden_conditions.dup
     if login = conditions.delete(:login)
-      where(conditions.to_hash).where(["lower(email) = ? OR username = ?", login.downcase, login]).first
+      where(conditions.to_hash).where(["lower(email) = ?", login.downcase]).first ||
+      where(conditions.to_hash).where(["username = ?", login]).first
     elsif conditions.has_key?(:username) || conditions.has_key?(:email)
       where(conditions.to_hash).first
     end