assume(x>y); is(x^ >y^2) problem

I am having trouble with assume() and is().  
With current cvs and both:
 - irix6.5 with clisp
 - mingw with gcl

I understand this works with macsyma, but can't test that.

Maxima 5.9.0pre-cvs (with enhancements by W. Schelter).
Licensed under the GNU Public License (see file COPYING)
(C1) assume(x > y);
(D1)                                [x > y]
(C2) is(x>y);
(D2)                                 TRUE
(C3) is(2*x > 2*y);
(D3)                                 TRUE
(C4) is(x^2 > y^2);
MACSYMA was unable to evaluate the predicate:
 2    2
x  > y
 -- an error.  Quitting.  To debug this try DEBUGMODE(TRUE);)