Hey Robert,
I've looked into this issue and it seems that it is a bug in ECL. Even on
idempotent defpackage definitions it first removes use-list and then re-adds
it, while the different part of the code enforces the lock. I've added the
ticket to our tracker:
https://gitlab.com/embeddable-com
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>.
```
