Fix empty interval
Fix empty interval

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