$ git clone -n https://src.fedoraproject.org/rpms/rust-arrayvec.git /var/lib/mock/f45-build-40132-768/root/chroot_tmpdir/scmroot/rust-arrayvec
Cloning into '/var/lib/mock/f45-build-40132-768/root/chroot_tmpdir/scmroot/rust-arrayvec'...
$ git fetch origin 0f0400dec947668a483b89813e9c0fffd977b13b:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-arrayvec
 * [new ref]         0f0400dec947668a483b89813e9c0fffd977b13b -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 0f0400d Update to version 0.7.8; Fixes RHBZ#2496537