message: Improve wording of comment.
diff: -;; Test that constant folding which overflows doesn't produce an undefined value.
  -;; Changing these tests to move the constants to the caller hides the bug.
  +;; Test that constant folding an operation that overflows doesn't produce an
  +;; undefined value. Changing these tests to move the constants to the
  +;; assert_return line hides the bug.
  (module
  ;; shl
  