permissionsdao: no silent fallback to user-permissions if we find none for user

database/permissionsdaosqlite.h

@@ -8,7 +8,7 @@ class PermissionsDaoSqlite : public PermissionsDao, protected SqliteDao
   public:
 	PermissionsDaoSqlite();
 
-	Permissions find(std::string pagename, std::string username) override;
+	std::optional<Permissions> find(std::string pagename, std::string username) override;
 	using SqliteDao::SqliteDao;
 };