Comment 7 for bug 1739514

Manual test that the problem is fixed:

sbcl
(load "~/quicklisp/setup") ;; using a 2017 version of Quicklisp
(load-system :cl-logic) ;; load it once
(plan-actions (nth-value 1 (operate 'load-op "cl-logic"))) ;; load it a second time

If the problem is fixed, the last form return NIL as there's nothing to do.

If the bug is still present, it returns a long list the first element of which is:
(#<DEFINE-OP > . #<SYSTEM "quine-mccluskey">)
but quine-mccluskey is semantically a secondary system (though its name is that of a non-existent primary system), and this DEFINE-OP is invalid and shouldn't be there.