$ git clone -n https://src.fedoraproject.org/rpms/image-builder.git /var/lib/mock/f43-build-58944866-6569371/root/chroot_tmpdir/scmroot/image-builder
Cloning into '/var/lib/mock/f43-build-58944866-6569371/root/chroot_tmpdir/scmroot/image-builder'...
$ git fetch origin 2ce9eead8f8e462a54d1c1b49dffe55e7adcc302:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/image-builder
 * [new ref]         2ce9eead8f8e462a54d1c1b49dffe55e7adcc302 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 2ce9eea Update to 17 upstream release