Comment 12 for bug 1465709

ASDF 1 historically allowed for version numbers in components. While almost no one uses this feature, I remember seeing with horror that some systems in Quicklisp were annotating components with version numbers, while fixing another issue with ASDF -- a run of cl-test-grid with a modified ASDF would tell for sure if that's still the case. Sigh.

I don't condone the use of :version for anything but a system. I believe it's a bug that ASDF allows it, and that ASDF can't conceivably do anything useful with it, nor is it ASDF's job to handle file version within a repository. That's what git is for.

Still, removing this feature is a backward-compatibility hassle, and requires hard work from whoever is going to make that change possible: run cl-test-grid, get all offenders to fix their .asd files, and if it happens in an unmaintained system, fork it and fix the fork.