$ git clone -n https://src.fedoraproject.org/rpms/rust-serial_test.git /var/lib/mock/f40-build-2658021-66917/root/chroot_tmpdir/scmroot/rust-serial_test
Cloning into '/var/lib/mock/f40-build-2658021-66917/root/chroot_tmpdir/scmroot/rust-serial_test'...
$ git fetch origin 0d0090860734de5fd3ae6eade151f88b1d1eee46:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-serial_test
 * [new ref]         0d0090860734de5fd3ae6eade151f88b1d1eee46 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 0d00908 Update to 3.0.0 (rhbz#2257120)