$ git clone -n https://src.fedoraproject.org/rpms/nbdkit.git /var/lib/mock/f39-build-1879199-42749/root/chroot_tmpdir/scmroot/nbdkit
Cloning into '/var/lib/mock/f39-build-1879199-42749/root/chroot_tmpdir/scmroot/nbdkit'...
$ git fetch origin d8bbfaccd846cf00e75290547dc6a08ee24caa7d:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/nbdkit
 * [new ref]         d8bbfaccd846cf00e75290547dc6a08ee24caa7d -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at d8bbfac Use the correct sources for ths branch