hash.rb in mutant-0.11.28

- old
+ new

@@ -34,10 +34,12 @@
             children :key, :value
 
           private
 
             def dispatch
-              emit_key_mutations
+              emit_key_mutations do |mutation|
+                !mutation.eql?(s(:nil))
+              end
               emit_value_mutations
             end
 
           end # Pair
         end # Hash