(user-homedir-pathname) not a constant?

[philpot]

dixiechicks.isi.edu 50%  ccl -n
Welcome to Clozure Common Lisp Version 1.4-r14334M  (LinuxX8632)!
? (user-homedir-pathname)
#P"/nfs/isd3/philpot/"

so far so good, but...

? (let ((*default-pathname-defaults*
          (make-pathname :directory '(:absolute "tmp")
             :name "dummy"
             :type "txt"
             :version :newest)))
   (user-homedir-pathname))
#P"/"
? (let ((*default-pathname-defaults* #p"/tmp/a.b"))
    (user-homedir-pathname))
#P"/nfs/isd3/philpot/a.b"

Looks like some merging is going on, but why?

As I read the CLHS, user-homedir-pathname is supposed to return either a (presumably constant) pathname sans name, type, and version components -- or NIL.

Is this behavior conformant?

Andrew 

[rme]

r14344 (in the trunk) changes user-homedir-pathname so it doesn't call truename (and therefore doesn't call merge-pathnames).