Comment 2 for bug 1626994

It was a subtle bug in ASDF indeed, due to an interaction between *load-system-operation* being load-bundle-op rather than load-op on ECL, and the use of required-components. The very subtle solution is now documented in suitable comments.

Fix included in CR !43:
https://gitlab.common-lisp.net/asdf/asdf/merge_requests/43