$ git clone -n https://src.fedoraproject.org/rpms/zig.git /var/lib/mock/f43-build-side-110462-58996176-6570093/root/chroot_tmpdir/scmroot/zig
Cloning into '/var/lib/mock/f43-build-side-110462-58996176-6570093/root/chroot_tmpdir/scmroot/zig'...
$ git fetch origin c7d17d37d7e1ce73548e84714d398759ee827dc3:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/zig
 * [new ref]         c7d17d37d7e1ce73548e84714d398759ee827dc3 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at c7d17d3 upload new sources