More new warnings from ASDF 3.3, this time I have no idea what it means.
WARNING: Computing just-done stamp in plan NIL for action (ASDF/LISP-ACTION:LOAD-OP "system"), but dependency (ASDF/FIND-SYSTEM:DEFINE-OP
"system") wasn't done yet!
The .asd file is not public, but it looks perfectly normal without using any complicated features.