In the regression test results for a bug fix to ASDF (https://gitlab.common-lisp.net/asdf/asdf/-/jobs/63801), I see this error which I don't understand at all:

Cannot unuse package #<"COMMON-LISP" package> from locked package #<"PACKAGE-INFERRED-SYSTEM-TEST/SBCL-EXT-LOCK" package>.

The line that seems to be causing this is the following (in a test system):

(defpackage package-inferred-system-test/sbcl-ext-lock
  (:use :cl)
  #+(or sbcl ecl) (:lock t)
  (:export #:implemented-by-other-package))

More discussion about this is in ASDF Merge Request 226: https://gitlab.common-lisp.net/asdf/asdf/-/merge_requests/226

The underlying issue is to try to make sure that implementation specific defpackage extensions (like :lock) don't cause ASDF's defpackage groveler to fail when working with package-defined systems.

Thanks for any advice!