A user-supplied allocator function is not called.

The test checks to make sure that a user-supplied allocator function is actually called during the construction of a unordered_multiset object where one of the template parameters is the pointer to the user-supplied allocator function.

While at least some of the unordered_multiset constructor functions appear to utilize the user-supplied allocator function, there are also some that do not and in this particular test, one of the constructors that does not call the user-supplied allocator function is called. The test is monitoring whether or not the user-supplied allocator function gets called via a global flag, and since the allocator function is not called, the test fails.