quote doesn't produce a fresh object

[Don Bashford]

(defun myfun (x)
  (let ((xs '(nil)))
    (print xs)
    (setcar xs "foo"))
  t)

On first invocation, (myfun 'arg) prints (nil) and returns t, as
expected.  But on second invocation, it prints ("foo").  It seems in the
second invocation, the let variable xs gets the old object from the
previous invocation.  If '(nil) is changed to (list nil) in myfun, the
problem does not occur, so the problem is with quote, not with let.

GNU Emacs 21.2.1 (i386-redhat-linux-gnu, X toolkit, Xaw3d scroll bars)
of 2002-04-08 on porky.devel.redhat.com

(Also occurs with 21.3 from redhat)

-Don