Sequence-reference variables with `&map` can't be recursive about loopy

[okamsn]

This might also be a problem with cl-subseq, or some interaction of multiple
things.

elt also has this problem

;; = > [0 1 2 3 4 5 6]
(let ((arr (vector 0 1 2 3 4 5 6)))
  (setf (elt (cl-subseq arr 3) 0)
        27)
  arr)

but using the hash-table functions does not

;; => [27 1 2]
(let ((map (make-hash-table)))
  (puthash 3 (vector 0 1 2) map)
  (setf (elt (gethash 3 map) 0) 27)
  (gethash 3 map))