fix(library/parray): race conditions
fix(library/parray): race conditions

dselsam/lean,avigad/lean,leanprover-community/lean,dselsam/lean,fpvandoorn/lean,fpvandoorn/lean,leodemoura/lean,dselsam/lean,leanprover/lean,avigad/lean,johoelzl/lean,rlewis1988/lean,fpvandoorn/lean,leanprover/lean,dselsam/lean,rlewis1988/lean,rlewis1988/lean,leanprover-community/lean,avigad/lean,leanprover/lean,digama0/lean,avigad/lean,leodemoura/lean,leodemoura/lean,digama0/lean,leanprover/lean,rlewis1988/lean,Kha/lean,leanprover/lean,leodemoura/lean,Kha/lean,leanprover-community/lean,dselsam/lean,johoelzl/lean,digama0/lean,digama0/lean,digama0/lean,avigad/lean,leanprover-community/lean,leanprover-community/lean,leanprover/lean,digama0/lean,fpvandoorn/lean,fpvandoorn/lean,johoelzl/lean,Kha/lean,johoelzl/lean,fpvandoorn/lean,leodemoura/lean,johoelzl/lean,avigad/lean,johoelzl/lean,leodemoura/lean,Kha/lean,leanprover-community/lean,rlewis1988/lean,Kha/lean,dselsam/lean,Kha/lean,rlewis1988/lean