$ git clone -n https://src.fedoraproject.org/rpms/rust-nix.git /var/lib/mock/f45-build-43360-802/root/chroot_tmpdir/scmroot/rust-nix
Cloning into '/var/lib/mock/f45-build-43360-802/root/chroot_tmpdir/scmroot/rust-nix'...
$ git fetch origin ef788f6f657bcd997a3f1c8e0de1c2cc1a4535be:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-nix
 * [new ref]         ef788f6f657bcd997a3f1c8e0de1c2cc1a4535be -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at ef788f6 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild