REARRAY complains about non-numeric size argument

REARRAY complains if the size argument is not numeric.
Example:

N: 8$
ARRAY (aa, float, 2^N)$ /* OK!! */
REARRAY (aa, 3^N)$ /* OOPS !! "Argument X
is not a NUMBER" */

There is an ancient FFT demo file,
.../share/numeric/fft.dem, which uses REARRAY with an
expression argument. So perhaps it did work at some
point in the past.

I guess that REARRAY could attempt to evaluate its size
argument if it's not numeric. I don't know what is the
usual course of action for Maxima functions.

I'm running Maxima 5.9.1 (cmucl) on linux.