$ git clone -n https://src.fedoraproject.org/rpms/rust-gio-sys0.19.git /var/lib/mock/f42-build-side-1-3502173-45977/root/chroot_tmpdir/scmroot/rust-gio-sys0.19
Cloning into '/var/lib/mock/f42-build-side-1-3502173-45977/root/chroot_tmpdir/scmroot/rust-gio-sys0.19'...
$ git fetch origin ae8fe7fc0f7a4962435b234862efeb59c153dc58:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-gio-sys0.19
 * [new ref]         ae8fe7fc0f7a4962435b234862efeb59c153dc58 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at ae8fe7f compat package no longer needed