Checkable: Don't count duplicated child dependencies twice

Author: yhabteab

lib/icinga/checkable-dependency.cpp

@@ -173,11 +173,14 @@ int Checkable::GetAllChildrenCount(int rstack) const
 		return 0;
 	}
 
+	std::set<Checkable*> seenChildren; // To avoid false positives in case of duplicated dependencies.
 	int count = 0;
 	// Actually, incrementing the rstack should be done once outside the loop here, but since IsReachable()
 	// applies the limit the exact same way, it should be fine to limit the sum of calls to 256 here as well.
 	for (auto& dependency: GetReverseDependencies()) {
-		count += dependency->GetChild()->GetAllChildrenCount(rstack + 1) + 1;
+		if (auto child(dependency->GetChild()); seenChildren.insert(child.get()).second) {
+			count += child->GetAllChildrenCount(rstack + 1) + 1;
+		}
 	}
 
 	return count;