$ git clone -n https://src.fedoraproject.org/rpms/bird.git /var/lib/mock/f39-build-1506953-35217/root/chroot_tmpdir/scmroot/bird
Cloning into '/var/lib/mock/f39-build-1506953-35217/root/chroot_tmpdir/scmroot/bird'...
$ git fetch origin e4cf9cbb89afdd279e2d62cda4c6c1c34373b715:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/bird
 * [new ref]         e4cf9cbb89afdd279e2d62cda4c6c1c34373b715 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at e4cf9cb Upgrade to 2.14 (#2242616)