$ git clone -n https://src.fedoraproject.org/rpms/rust-jobserver.git /var/lib/mock/f45-build-42781-796/root/chroot_tmpdir/scmroot/rust-jobserver
Cloning into '/var/lib/mock/f45-build-42781-796/root/chroot_tmpdir/scmroot/rust-jobserver'...
$ git fetch origin 7b77a5a825e95b04a4f9e78a0045a79535022ee3:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-jobserver
 * [new ref]         7b77a5a825e95b04a4f9e78a0045a79535022ee3 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 7b77a5a Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild