$ git clone -n https://src.fedoraproject.org/rpms/rust-cfg-expr0.17.git /var/lib/mock/f45-build-40743-775/root/chroot_tmpdir/scmroot/rust-cfg-expr0.17
Cloning into '/var/lib/mock/f45-build-40743-775/root/chroot_tmpdir/scmroot/rust-cfg-expr0.17'...
$ git fetch origin 2a18ad1cb6e933512965a16a670bee4414c738e1:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-cfg-expr0.17
 * [new ref]         2a18ad1cb6e933512965a16a670bee4414c738e1 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 2a18ad1 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild