$ git clone -n https://src.fedoraproject.org/rpms/rust-gtk-sys0.17.git /var/lib/mock/f38-build-side-43-rust-devel-1419714-31460/root/chroot_tmpdir/scmroot/rust-gtk-sys0.17
Cloning into '/var/lib/mock/f38-build-side-43-rust-devel-1419714-31460/root/chroot_tmpdir/scmroot/rust-gtk-sys0.17'...
$ git fetch origin b6b2917b5da80d77e3e815bb27a788dddd7613d7:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-gtk-sys0.17
 * [new ref]         b6b2917b5da80d77e3e815bb27a788dddd7613d7 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b6b2917 Initial import (gtk-sys 0.17 compat package)