The parts with `-j1` in this formula should only be occurring during installation. This one is for installation of the bindist, line 146 is for installation of the built source (see line 144). The actual build process should use multiple jobs (and it is still slow regardless).

As for whether the race condition still occurs, I believe the answer is yes. In any case, removing `-j1` shouldn't make a significant difference in build+install time unless something else is wrong.