HeapRegionManager::par_iterate contains the following comment:

    // However, if the iteration is specified as concurrent, the values for
    // is_starts_humongous and is_continues_humongous can not be trusted,
    // and we should just blindly iterate over regions regardless of their
    // humongous status.

The method does not have a "concurrent" parameter for a long time. I think this comment relates to the time when the humongous starts HeapRegion actually covered all regions the humongous object covered.
Either way, remove.