fix(library/module): deadlock
fix(library/module): deadlock

Signed-off-by: Leonardo de Moura <7610bae85f2b530654cc716772f1fe653373e892@microsoft.com>

fgdorais/lean,soonhokong/lean-osx,johoelzl/lean,soonhokong/lean-windows,avigad/lean,soonhokong/lean,fpvandoorn/lean,rlewis1988/lean,sp3ctum/lean,johoelzl/lean,leodemoura/lean,levnach/lean,johoelzl/lean,Kha/lean,soonhokong/lean-windows,javra/lean,rlewis1988/lean,digama0/lean,javra/lean,eigengrau/lean,leanprover-community/lean,fgdorais/lean,dselsam/lean,fpvandoorn/lean,levnach/lean,fpvandoorn/lean,sp3ctum/lean,leanprover/lean,fgdorais/lean,dselsam/lean,soonhokong/lean-osx,sp3ctum/lean,levnach/lean,rlewis1988/lean,avigad/lean,soonhokong/lean,leanprover/lean,digama0/lean,leanprover/lean,eigengrau/lean,fpvandoorn/lean2,soonhokong/lean,c-cube/lean,htzh/lean,UlrikBuchholtz/lean,htzh/lean,c-cube/lean,javra/lean,fpvandoorn/lean2,avigad/lean,soonhokong/travis_test,sp3ctum/lean,fpvandoorn/lean2,avigad/lean,digama0/lean,fpvandoorn/lean,leanprover-community/lean,fgdorais/lean,javra/lean,dselsam/lean,leodemoura/lean,dselsam/lean,johoelzl/lean,UlrikBuchholtz/lean,soonhokong/lean-windows,Kha/lean,eigengrau/lean,Kha/lean,leanprover-community/lean,eigengrau/lean,fgdorais/lean,soonhokong/lean,htzh/lean,eigengrau/lean,Kha/lean,UlrikBuchholtz/lean,levnach/lean,javra/lean,johoelzl/lean,leanprover/lean,leanprover/lean,levnach/lean,Kha/lean,soonhokong/lean-osx,soonhokong/travis_test,leanprover-community/lean,soonhokong/travis_test,soonhokong/lean-osx,digama0/lean,leanprover/lean,leanprover-community/lean,fpvandoorn/lean2,leodemoura/lean,digama0/lean,UlrikBuchholtz/lean,UlrikBuchholtz/lean,avigad/lean,dselsam/lean,fpvandoorn/lean2,fgdorais/lean,soonhokong/lean-osx,dselsam/lean,Kha/lean,soonhokong/lean-windows,c-cube/lean,leodemoura/lean,fpvandoorn/lean,c-cube/lean,soonhokong/lean,fpvandoorn/lean,sp3ctum/lean,soonhokong/lean-windows,digama0/lean,johoelzl/lean,soonhokong/travis_test,rlewis1988/lean,leanprover-community/lean,leodemoura/lean,avigad/lean,rlewis1988/lean,htzh/lean,rlewis1988/lean,leodemoura/lean,htzh/lean,c-cube/lean