orderless([rat(a)],b) bug



Using maxima 5.9.0rc3  and CMUCL, I get an error with 
orderless([rat(a)],b).   Under Maxima 5.5 and GCL (Windows XP)
it works okay.   Is this a 5.9.0rc3 problem or this bug unique to CMUCL / 
maxima?  A fix? 

(C1) build_info();

Maxima version: 5.9.0rc3
Maxima build date: 19:1 11/7/2002
host type: i686-pc-linux-gnu
lisp-implementation-type: CMU Common Lisp
lisp-implementation-version: 18d

(D1) 
(C2) orderlessp([rat(a)],b);


Type-error in KERNEL::OBJECT-NOT-LIST-ERROR-HANDLER:
   #:|a1138| is not of type LIST

Restarts:
  0: [MACSYMA-QUIT] Macsyma top-level
  1: [ABORT       ] Skip remaining initializations.

Debug  (type H for help)

(ORDFNA (#:|a1138| 1 1) |$b|)
Source: 
; File: /home/barton/mac2/maxima-5.9.0rc3/src/simp.lisp
(CAAR E)
0] 0
Maxima restarted.
(C3) :lisp(trace alike alike1 SPECREPCHECK);

(ALIKE ALIKE1 SPECREPCHECK)
(C3) orderlessp([rat(a)],b);

  0: (ALIKE1 |$a| |$a|)
  0: ALIKE1 returned T
  0: (ALIKE1 |$a| |$a|)
  0: ALIKE1 returned T
  0: (SPECREPCHECK ((MLIST SIMP) (# # . 1)))
  0: SPECREPCHECK returned ((MLIST SIMP) (# # . 1))
  0: (SPECREPCHECK |$b|)
  0: SPECREPCHECK returned |$b|
  0: (ALIKE1 ((MLIST SIMP) (# # . 1)) |$b|)
  0: ALIKE1 returned NIL


Type-error in KERNEL::OBJECT-NOT-LIST-ERROR-HANDLER:
   #:|a1138| is not of type LIST

Restarts:
  0: [MACSYMA-QUIT] Macsyma top-level
  1: [ABORT       ] Skip remaining initializations.

Debug  (type H for help)

(ORDFNA (#:|a1138| 1 1) |$b|)
Source: (CAAR E)
0] 0
Maxima restarted.

--------------------------------------------------------

Maxima 5.5 Tue Dec 5 16:55:33 2000 (with enhancements by W. Schelter).
Licensed under the GNU Public License (see file COPYING)
(C1) orderlessp([rat(a)],b);
(D1)                             TRUE
(C2) 
----------------------------------------------------------

Barton

P.S.  I encountered this bug while working on a new set package.