Comment 2 for bug 1988892

We've gone down this road before. https://bugs.launchpad.net/sbcl/+bug/1823442 makes the case for users choosing to upgrade ASDF on their own, on top of the bundled ASDF.

I intend to remove the use of ASDF to build contribs, so the trade-offs will be different, I think for the better. Google uses https://bazel.build/ to build the contribs, which is a viable competitor to ASDF that previous discussions allude to. But in the SBCL distribution I'd like to avoid using either bazel or ASDf.