How to compare unordered_set of unordered_set of integers in c++?

I need to test two sets for equality in my unit test.

#include <unordered_set> bla bla bla


        unordered_set<unordered_set<int>> exampleOutput;
        unordered_set<int> firstCluster;
        firstCluster.insert(1);
        firstCluster.insert(2);
        unordered_set<int> secondCluster;
        secondCluster.insert(3);
        secondCluster.insert(4);

unordered_set<unordered_set<int>> outputAsSet;
        for (auto e: output) {
            vector<int> cluster = e.toVector();
            outputAsSet.insert(cluster.begin(), cluster.end());
        }
        TS_ASSERT_EQUALS(exampleOutput, outputAsSet);

Which gives me the error

opt/local/include/gcc48/c++/bits/hashtable_policy.h: In instantiation of 'struct std::__detail::_Hash_code_base, std::unordered_set, std::__detail::_Identity, std::hash >, std::__detail::_Mod_range_hashing, std::__detail::_Default_ranged_hash, true>':

My guess is that stl is too stupid compare set of sets, because it can't compute the hash inner set. But maybe I am wrong.

Of course I can write all comparisons by hand comparing each inner set with all others in exampleSet, but who wants to do that...