That way, we would not have to rebuild anything (it temporarily breaks
GNU/Hurd though, but that’s the cost we’d have to pay.)

How does that sound?

The actual fix, for the next core-updates cycle, would be to delay
evaluation of ld-wrapper-boot0.

I guess this bug shows that nobody tried to get substitutes for
core-updates on non-x86_64 platforms.  :-/

Thanks a lot for the heads-up!

Ludo’.