Dear Daniel,
if you're willing to fork ASDF over make-build, would putting a make-build compatibility function back in ASDF make you adopt the upstream version again? I have an implementation for it at the end of https://gitlab.common-lisp.net/asdf/asdf/merge_requests/34 but I'd need you to provide some more test case (a simple one exists somewhere in some old version in git).
There were many fixes in ASDF 3.2 and 3.3, including ECL-specific fixes, compared to the 3.1.7 from which you forked, and forking is just more work for both you and us.
—♯ƒ • François-René ÐVB Rideau •Reflection&Cybernethics• http://fare.tunes.org Social peace will come when the socialists will love the poor more than they hate the rich. — Not Golda Meir