$ git clone -n https://src.fedoraproject.org/rpms/rust-nix0.27.git /var/lib/mock/f45-build-43359-802/root/chroot_tmpdir/scmroot/rust-nix0.27
Cloning into '/var/lib/mock/f45-build-43359-802/root/chroot_tmpdir/scmroot/rust-nix0.27'...
$ git fetch origin 988d31b0e385bde1d164637e4e58c0eff36869ff:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-nix0.27
 * [new ref]         988d31b0e385bde1d164637e4e58c0eff36869ff -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 988d31b Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild