$ git clone -n https://src.fedoraproject.org/rpms/debmirror.git /var/lib/mock/f42-build-side-1-3584208-46892/root/chroot_tmpdir/scmroot/debmirror
Cloning into '/var/lib/mock/f42-build-side-1-3584208-46892/root/chroot_tmpdir/scmroot/debmirror'...
$ git fetch origin ea1b4b2bb9ed4058015587d35e78a682884ec96e:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/debmirror
 * [new ref]         ea1b4b2bb9ed4058015587d35e78a682884ec96e -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at ea1b4b2 Update to 2.46