I have incorporated Juanjo's patches, together with my slight modification, and tested them on Mac OS X against:
ACL ACL modern ABCL CCL CLISP SBCL
... and it passes all of these tests.
So I am pushing a new ASDF version (2.017.2).
Juanjo, will you please test this ASAP? Also, will anyone who has a linux box set up with all the latest and greatest lisp releases give it a whirl? I will test on 64-bit ACL there, and a slightly-old SBCL.
Cheers, r