$ git clone -n https://src.fedoraproject.org/rpms/rust-fallible_collections.git /var/lib/mock/f38-build-side-42-init-devel-1394469-31050/root/chroot_tmpdir/scmroot/rust-fallible_collections
Cloning into '/var/lib/mock/f38-build-side-42-init-devel-1394469-31050/root/chroot_tmpdir/scmroot/rust-fallible_collections'...
$ git fetch origin 2ccfd42e3127946c38b4a7692d8c223bb6e86c84:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-fallible_collections
 * [new ref]         2ccfd42e3127946c38b4a7692d8c223bb6e86c84 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 2ccfd42 Update to version 0.4.9 (rhbz#2219129)