"trigrat" caught in infinite loop - depending on how you call it

Hello Maxima users,

I have discovered a very strange bug in Maxima, which I am about to 
report on SourceForge.
But nevertheless, I want to ask if any of you has come across this one 
or might be able to help me circumvent it.

The following works:

e : 2*x/(sqrt(y)+x) - (x^2/((sqrt(y)+x)^2));
trigrat(e);
trigrat(xthru(e));

But when I do this:

( trigrat(e), trigrat(xthru(e)) )

or

[ trigrat(e), trigrat(xthru(e)) ]

the second "trigrat" call inside will hang, i.e. Maxima will run on 100% 
CPU and will never return.
So: evaluating both lines separately works, but evaluating them together 
or inside a function will cause the "bug".

Strangely, everything works fine when I swap the expressions:

( trigrat(e), trigrat(xthru(e)) );   /* loops forever */
( trigrat(xthru(e)), trigrat(e) );   /* works */

I can't find a pattern ... it seems very mysterious to me.
Any idea what might be happening here?

Regards,
David Scherfgen