fix to dup mounters cache on mount

Author: rajyan

lib/carrierwave/mount.rb

@@ -428,6 +428,11 @@ def write_uploader(column, identifier); end
 
     private
 
+      def initialize_dup(other)
+        @_mounters = @_mounters.dup
+        super
+      end
+
       def _mounter(column)
         # We cannot memoize in frozen objects :(
         return Mounter.build(self, column) if frozen?

lib/carrierwave/orm/activerecord.rb

@@ -43,7 +43,6 @@ def reload(*)
         # Reset cached mounter on record dup
         def initialize_dup(other)
           old_uploaders = _mounter(:"#{column}").uploaders
-          @_mounters =  @_mounters.dup
           @_mounters[:"#{column}"] = nil
           super
           # The attribute needs to be cleared to prevent it from picked up as identifier