Isn't that how it works now? If so, isn't that supposed to enable you to make a change/tweak in a bundle w/o overriding the entire bundle?
I think if you have a local bundle the support path also points to that local bundle, even if you only have a simple snippet overridden. So it might be, that the bundle was copied (old way) way ago and the support directory outdated. Otherwise it should not have found the necessary files in the support path at all…
Soryu.