$ git clone -n https://src.fedoraproject.org/rpms/rubygem-posix-spawn.git /var/lib/mock/f42-build-865202-172845/root/chroot_tmpdir/scmroot/rubygem-posix-spawn
Cloning into '/var/lib/mock/f42-build-865202-172845/root/chroot_tmpdir/scmroot/rubygem-posix-spawn'...
$ git fetch origin 7bd9d98fbcd53d46355b3e89469c139e9590aeec:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rubygem-posix-spawn
 * [new ref]         7bd9d98fbcd53d46355b3e89469c139e9590aeec -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 7bd9d98 Rebuild for https://fedoraproject.org/wiki/Changes/Ruby_3.4