$ git clone -n https://src.fedoraproject.org/rpms/rust-platforms.git /var/lib/mock/f42-build-side-1-3583679-46890/root/chroot_tmpdir/scmroot/rust-platforms
Cloning into '/var/lib/mock/f42-build-side-1-3583679-46890/root/chroot_tmpdir/scmroot/rust-platforms'...
$ git fetch origin c6116dec73d107000e04287bb2efcc3e5dd6a1ad:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-platforms
 * [new ref]         c6116dec73d107000e04287bb2efcc3e5dd6a1ad -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at c6116de Update to version 3.6.0; Fixes RHBZ#2370029