DO Bug
Here's what your bad DO expands into in NCOMPLR, which looks
ok:

((LAMBDA (OLD NEW L I) 
  (PROG NIL 
   G0002(COND ((= I N) (RETURN L)))
	(SETQ OLD
	      (PROG2 NIL
		     NEW
		     (SETQ NEW
			   (PROG2 NIL
				  (1+ NEW)
				  (SETQ L
					(PROG2 NIL
					       (CONS (LIST OLD NEW) L)
					       (SETQ I (1+ I))))))))
	(GO G0002)))
 1
 2
 NIL
 0)

Here it is with the NIL DO expander:

((LAMBDA (OLD NEW L I) 
  (PROG NIL 
	(GO |T..3|)
   |T..2|
	(SETQ OLD
	      (PROG1 NEW
		     (SETQ NEW
			   (PROG1 (1+ NEW)
				  (SETQ L
					(PROG1 (CONS (LIST OLD NEW) L)
					       (SETQ I (1+ I))))))))
   |T..3|
	(COND ((NOT (= I N)) (GO |T..2|)))
	(RETURN L)))
 1
 2
 NIL
 0)
* 
			-rpg-