Fix commit 9622b45: need to remember safe sets on current level to generate next
Fix commit 9622b45: need to remember safe sets on current level to generate next

isse-augsburg/ssharp,maul-esel/ssharp,maul-esel/ssharp,maul-esel/ssharp,maul-esel/ssharp,isse-augsburg/ssharp,isse-augsburg/ssharp,isse-augsburg/ssharp,isse-augsburg/ssharp