Fix memory corruption bug
Fix memory corruption bug

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

levnach/lean,soonhokong/lean,UlrikBuchholtz/lean,UlrikBuchholtz/lean,soonhokong/lean-windows,soonhokong/lean,soonhokong/lean,digama0/lean,soonhokong/lean-osx,leanprover-community/lean,dselsam/lean,rlewis1988/lean,javra/lean,UlrikBuchholtz/lean,Kha/lean,leanprover-community/lean,soonhokong/lean,leanprover/lean,soonhokong/lean-windows,htzh/lean,fgdorais/lean,avigad/lean,fpvandoorn/lean,johoelzl/lean,digama0/lean,rlewis1988/lean,fpvandoorn/lean,rlewis1988/lean,leodemoura/lean,fgdorais/lean,fpvandoorn/lean2,avigad/lean,soonhokong/lean-osx,fpvandoorn/lean2,soonhokong/lean-osx,eigengrau/lean,soonhokong/lean-windows,sp3ctum/lean,sp3ctum/lean,rlewis1988/lean,javra/lean,avigad/lean,johoelzl/lean,dselsam/lean,htzh/lean,johoelzl/lean,soonhokong/travis_test,fpvandoorn/lean,avigad/lean,leanprover-community/lean,eigengrau/lean,soonhokong/lean-windows,dselsam/lean,javra/lean,soonhokong/lean-osx,leanprover/lean,leanprover/lean,leodemoura/lean,leodemoura/lean,Kha/lean,digama0/lean,codyroux/lean0.1,levnach/lean,htzh/lean,leanprover/lean,soonhokong/lean,leodemoura/lean,johoelzl/lean,leodemoura/lean,johoelzl/lean,leanprover-community/lean,leanprover/lean,fpvandoorn/lean,c-cube/lean,soonhokong/lean-windows,c-cube/lean,levnach/lean,rlewis1988/lean,codyroux/lean0.1,dselsam/lean,fpvandoorn/lean2,sp3ctum/lean,eigengrau/lean,fpvandoorn/lean2,fgdorais/lean,soonhokong/travis_test,rlewis1988/lean,fgdorais/lean,Kha/lean,javra/lean,leanprover-community/lean,levnach/lean,c-cube/lean,avigad/lean,johoelzl/lean,sp3ctum/lean,codyroux/lean0.1,soonhokong/travis_test,eigengrau/lean,digama0/lean,levnach/lean,avigad/lean,leanprover/lean,eigengrau/lean,fgdorais/lean,soonhokong/lean-osx,javra/lean,digama0/lean,fgdorais/lean,c-cube/lean,fpvandoorn/lean,fpvandoorn/lean,UlrikBuchholtz/lean,htzh/lean,sp3ctum/lean,Kha/lean,dselsam/lean,leodemoura/lean,dselsam/lean,soonhokong/travis_test,Kha/lean,Kha/lean,codyroux/lean0.1,digama0/lean,fpvandoorn/lean2,c-cube/lean,htzh/lean,UlrikBuchholtz/lean,leanprover-community/lean