Why pass an lvalue to a constructor that takes a const ref rvalue?

E.g:

#include <iostream>
#include <cstring>

using namespace std;

struct Square
{
    Square()
    {
        str = new char[10];
        strcpy(str, "Hello");
    }

    ~Square()
    {
        delete str;   
    }

    void print()
    {
        cout << "str = '" << str << "'" << endl;
    }

    char * str;    
};

class foo
{
public:
    typedef const Square & sqcref;
    typedef Square & sqref;
    foo(sqref && _ref)
    {
        fooStr = _ref.str;
        _ref.str = 0;
    }

    char * fooStr;
};

int main()
{
    Square s;
    s.print();
    foo f(s);
    s.print();
}

output:

str ='
Hello'str ='

Inside the constructor of a foo, it expects an rvalue to be Square &passed to a , but an Square &lvalue is passed in instead. Why did you do this?