Please keep the debbugs address cc'd.

an wrote (on Mon, 11 Mar 2013 at 11:39 -0500):

> If the offending file is "mule" then it is indeed a bug of Emacs since mule
> is a builtin lib, right?
>
> If "mule" in the warning does not mean the mule lib then warning gives too
> little helpful info for user to debug.

The warning is issued _by_ the mule.el library, it is not _about_ the
mule.el library.

A simple grep should find the offending file(s) in no time at all.