real world?

Oh, gods, yes, the libdrm/Mesa/driver-version combination nightmare is a tricky one I'd forgotten about. Of course that itself is sort of kernel-connected, because the only reason most of that stuff is revving so fast is because of changes on the kernel side :)

The go-back-in-time stuff is probably best supported by the Nix distro (no relation); the downside of that is that it requires an insane amount of recompilation whenever anything changes because it has no understanding of ABI-preservation conventions (assuming that all library users need to be rebuilt whenever a library is).