See the patch to active_support in changeset 6426, below. Not sure if your problem is the same, but sounds as if it could be. I didn't move all the way to edge, just applied the one patch, and my NoMethodError problems have vanished.
<http://dev.rubyonrails.org/ticket/6720> <http://dev.rubyonrails.org/ticket/6951> and http://dev.rubyonrails.org/changeset/6426
