$ git clone -n https://src.fedoraproject.org/rpms/rust-serde.git /var/lib/mock/f40-build-2251166-54117/root/chroot_tmpdir/scmroot/rust-serde
Cloning into '/var/lib/mock/f40-build-2251166-54117/root/chroot_tmpdir/scmroot/rust-serde'...
$ git fetch origin c6e7d42732222e742ae00e563ca4b4e78eb242e5:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-serde
 * [new ref]         c6e7d42732222e742ae00e563ca4b4e78eb242e5 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at c6e7d42 Update to version 1.0.195; Fixes RHBZ#2257011