">>" operator of std::normal_distribution doesn't work properly

Issue

">>" operator of std::normal_distribution doesn't work properly.

The following reproducer, test.cpp, is expected to output "OK" according to the C++ standard, but it actually outputs "NG".

      test.cpp:
      #include <random>
      #include <sstream>
      #include <cstdio>

      int main()
      {
        std::normal_distribution<> d1(7, 5);
        std::stringstream ss;

        ss << d1;

        std::normal_distribution<> d2;
        ss >> d2;

        if (d1 == d2) puts("OK");
        else puts("NG");

        return 0;
      }