$ git clone -n https://src.fedoraproject.org/rpms/rust-below-btrfs.git /var/lib/mock/f40-build-2061189-49167/root/chroot_tmpdir/scmroot/rust-below-btrfs
Cloning into '/var/lib/mock/f40-build-2061189-49167/root/chroot_tmpdir/scmroot/rust-below-btrfs'...
$ git fetch origin 772ea0b7ae75c1e0e88112758fa42ea3d3ac4b5f:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-below-btrfs
 * [new ref]         772ea0b7ae75c1e0e88112758fa42ea3d3ac4b5f -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 772ea0b Update to 0.7.1