-dev subpackage does not get build correctly for linux-postmarketos-stable

I'm trying to create a package that builds a kernel module and thus depends on the -dev subpackage of the kernel. It turns out that the linux-postmarketos-stable-dev package is never correctly generated.

To reproduce:

$ git checkout feature/wireguard
$ git build --force --arch=armhf wireguard-postmarketos-stable

It will crash with a dependency error:

ERROR: unsatisfiable constraints:
  linux-postmarketos-stable-dev (missing):
    required by: world[linux-postmarketos-stable-dev]

I verified that linux-postmarketos-stable-dev.apk does indeed not exist in the local repository, if I try to build it manually pmbootstrap complains that it package is already built.

If I --force it to build it does a whole kernel compilation but never actually creates the -dev.apk file.