$ git clone -n https://src.fedoraproject.org/rpms/rust-markup5ever_rcdom.git /var/lib/mock/f42-build-side-1-3588886-46951/root/chroot_tmpdir/scmroot/rust-markup5ever_rcdom
Cloning into '/var/lib/mock/f42-build-side-1-3588886-46951/root/chroot_tmpdir/scmroot/rust-markup5ever_rcdom'...
$ git fetch origin cbb0c41a44139df6aef32ac8867c717d46d6a27e:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-markup5ever_rcdom
 * [new ref]         cbb0c41a44139df6aef32ac8867c717d46d6a27e -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at cbb0c41 no longer needed