$ git clone -n https://src.fedoraproject.org/rpms/rust-darling_macro0.20.git /var/lib/mock/f45-build-41204-780/root/chroot_tmpdir/scmroot/rust-darling_macro0.20
Cloning into '/var/lib/mock/f45-build-41204-780/root/chroot_tmpdir/scmroot/rust-darling_macro0.20'...
$ git fetch origin 84af9a6c3ca96459da972236928e673864f4989e:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-darling_macro0.20
 * [new ref]         84af9a6c3ca96459da972236928e673864f4989e -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 84af9a6 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild