$ git clone -n https://src.fedoraproject.org/rpms/rust-config.git /var/lib/mock/f40-build-2175839-51067/root/chroot_tmpdir/scmroot/rust-config
Cloning into '/var/lib/mock/f40-build-2175839-51067/root/chroot_tmpdir/scmroot/rust-config'...
$ git fetch origin 7394670636f8c2f2123bf72124fe40ffd03ce78e:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-config
 * [new ref]         7394670636f8c2f2123bf72124fe40ffd03ce78e -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 7394670 Update to version 0.13.4; Fixes RHBZ#2250999