On Mon, 16 Jul 2018 18:55:11 +0100 (BST)
<pkill9@runbox.com> wrote:

> It would be good to keep the build directory though, since it's expected to exist, and it's easier to just download a module's source and compile it and test it.

I agree.

/run/booted-system/kernel/lib/modules/4.17.3-gnu is in the store anyway so it will be seen by the GC.

The fix would be in linux-libre.