COMPILE regression in Apr 2010 snapshot (?)

Helu, here is an unpolished test case to show the problem:

  -=-=-
(defmacro frob-keyvals-string (string)
  (with-input-from-string (stream string)
    `(progn ,@(loop for key = (let ((x (read stream nil stream)))
				(if (eq x stream) (loop-finish) x))
		    for val = (read stream)
		    for comment = (read stream)
		    collect (list 'defvar key (list 'quote val)
				  (string comment))))))

(frob-keyvals-string "
foo fooval foocomment
bar barval barcomment
car carval carcomment")

  -=-=-

When compiled with COMPILE-FILE in the 2010-04 snapshot, the above
snippet appears to recompile the macro definition as many times as
there are DEFVARs in the macro expansion.

--
Madhu