$ git clone -n https://src.fedoraproject.org/rpms/rust-constant_time_eq.git /var/lib/mock/f41-build-side-1-2991771-36005/root/chroot_tmpdir/scmroot/rust-constant_time_eq
Cloning into '/var/lib/mock/f41-build-side-1-2991771-36005/root/chroot_tmpdir/scmroot/rust-constant_time_eq'...
$ git fetch origin d2b5a5a4b83482dfae4b1f670e4b63a8783b837c:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-constant_time_eq
 * [new ref]         d2b5a5a4b83482dfae4b1f670e4b63a8783b837c -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at d2b5a5a Update to version 0.3.1; Fixes RHBZ#2308070