$ git clone -n https://src.fedoraproject.org/rpms/rust-test-case.git /var/lib/mock/f40-build-2259436-54370/root/chroot_tmpdir/scmroot/rust-test-case
Cloning into '/var/lib/mock/f40-build-2259436-54370/root/chroot_tmpdir/scmroot/rust-test-case'...
$ git fetch origin c6e72da725a6b5f00faa2c369cb28ce397e509c9:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-test-case
 * [new ref]         c6e72da725a6b5f00faa2c369cb28ce397e509c9 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at c6e72da Update to version 3.3.1; Fixes RHBZ#2250256