fix(shell/server): last snapshot may not be valid any more
fix(shell/server): last snapshot may not be valid any more

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