lib/mongoid/relations/referenced/many_to_many.rb in mongoid-2.4.0 vs lib/mongoid/relations/referenced/many_to_many.rb in mongoid-2.4.1

@@ -140,13 +140,11 @@
         # @return [ Many ] The relation.
         #
         # @since 2.0.0.rc.1
         def substitute(replacement)
           tap do |proxy|
-            if replacement != proxy.in_memory
-              proxy.purge
-              proxy.push(replacement.compact.uniq) if replacement
-            end
+            proxy.purge
+            proxy.push(replacement.compact.uniq) unless replacement.blank?
           end
         end
 
         # Get a criteria for the documents without the default scoping
         # applied.