$ git clone -n https://src.fedoraproject.org/rpms/rust-serde-big-array.git /var/lib/mock/f40-build-2657986-66917/root/chroot_tmpdir/scmroot/rust-serde-big-array
Cloning into '/var/lib/mock/f40-build-2657986-66917/root/chroot_tmpdir/scmroot/rust-serde-big-array'...
$ git fetch origin a7a3a734b2b746c207d235eb33101b23bbc47227:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-serde-big-array
 * [new ref]         a7a3a734b2b746c207d235eb33101b23bbc47227 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at a7a3a73 Update to version 0.5.1; Fixes RHBZ#2170888