perf(library/blast/congruence_closure): only copy parents that are still congruence roots
perf(library/blast/congruence_closure): only copy parents that are still congruence roots

rlewis1988/lean,levnach/lean,leanprover-community/lean,avigad/lean,leodemoura/lean,johoelzl/lean,digama0/lean,soonhokong/lean-osx,dselsam/lean,leanprover/lean,UlrikBuchholtz/lean,johoelzl/lean,leanprover-community/lean,fpvandoorn/lean,johoelzl/lean,soonhokong/lean,fpvandoorn/lean2,Kha/lean,soonhokong/lean-windows,dselsam/lean,levnach/lean,digama0/lean,Kha/lean,Kha/lean,fpvandoorn/lean2,digama0/lean,johoelzl/lean,leanprover/lean,fgdorais/lean,javra/lean,fgdorais/lean,soonhokong/lean-windows,digama0/lean,fpvandoorn/lean,leanprover/lean,fgdorais/lean,johoelzl/lean,fgdorais/lean,fpvandoorn/lean2,leanprover-community/lean,soonhokong/lean,soonhokong/lean,dselsam/lean,fgdorais/lean,javra/lean,rlewis1988/lean,UlrikBuchholtz/lean,avigad/lean,leanprover-community/lean,digama0/lean,digama0/lean,leodemoura/lean,soonhokong/lean,rlewis1988/lean,soonhokong/lean,leodemoura/lean,soonhokong/lean-osx,soonhokong/lean-windows,leanprover-community/lean,soonhokong/lean-osx,fpvandoorn/lean,soonhokong/lean-windows,levnach/lean,avigad/lean,leodemoura/lean,levnach/lean,rlewis1988/lean,fpvandoorn/lean,fpvandoorn/lean2,avigad/lean,Kha/lean,leanprover/lean,leanprover-community/lean,avigad/lean,fpvandoorn/lean2,UlrikBuchholtz/lean,levnach/lean,javra/lean,UlrikBuchholtz/lean,dselsam/lean,rlewis1988/lean,johoelzl/lean,javra/lean,Kha/lean,soonhokong/lean-windows,dselsam/lean,soonhokong/lean-osx,javra/lean,leodemoura/lean,soonhokong/lean-osx,UlrikBuchholtz/lean,Kha/lean,leanprover/lean,leanprover/lean,dselsam/lean,fpvandoorn/lean,fgdorais/lean,fpvandoorn/lean,avigad/lean,rlewis1988/lean,leodemoura/lean