$ git clone -n https://src.fedoraproject.org/rpms/ghc-hostname.git /var/lib/mock/f45-build-10380-416/root/chroot_tmpdir/scmroot/ghc-hostname
Cloning into '/var/lib/mock/f45-build-10380-416/root/chroot_tmpdir/scmroot/ghc-hostname'...
$ git fetch origin 981d491b2ae5f3733a998e2d249952a9032561b8:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/ghc-hostname
 * [new ref]         981d491b2ae5f3733a998e2d249952a9032561b8 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 981d491 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild