require-system fails to not load the second time around

[Faré]

;;;;; bug.asd:
(defsystem "bug" :components ((:file "a")))
(defvar *loaded-times* 0)
(incf *loaded-times*)
(format t "This asd file was loaded ~D times~%" *loaded-times*)

;;;;; a.lisp:
(defpackage :bug (:use :cl))
(in-package :bug)
(eval-when (:load-toplevel) (defparameter *time* :load-toplevel))
(eval-when (:compile-toplevel) (defparameter *time* :compile-toplevel))
(eval-when (:execute) (defparameter *time* :execute))
(eval-when (:load-toplevel :compile-toplevel :execute) (format t "~&It's ~A time!~%" *time*))

(require-system :bug)
(require-system :bug) ;; recompiles the system.

[Faré (fahree)]

There is now the beginning of a test case at the end of test-force.script (as of 3.1.7.17).

[Faré (fahree)]

I believe this is now fixed, thanks to the detective work of Daniel Kochmanski.

See !13, !16, !21 on gitlab:
https://gitlab.common-lisp.net/asdf/asdf/merge_requests/13
https://gitlab.common-lisp.net/asdf/asdf/merge_requests/16
https://gitlab.common-lisp.net/asdf/asdf/merge_requests/21