Die Bourgeoisie, wo sie zur Herrschaft gekommen, hat alle feudalen, patriarchalischen, idyllischen Verhältnisse zerstört. (Communist Manifesto, section 1, par 14) "The bourgeoisie, wherever it has come to power, has ..."
Why is there not an auxiliary "ist" with "gekommen" in the relative clause (if that is what it is) introduced by "wo"?