c++98/c++03 constructor overloading

Hi,

With gcc-4.2 and earlier, and with subsequent versions of gcc when
using the -std=c++98 option, the following code fails to compile:

--------------------------

#include <iostream>
#include <ostream>

enum ByRef {by_ref};

template <class T>
class MyClass {
  T t;
public:
  MyClass(const T& arg): t(arg) { // (1)
    std::cout << "Without ByRef tag" << std::endl;
  }
  MyClass(T arg, ByRef): t(arg) { // (2)
    std::cout << "With ByRef tag" << std::endl;
  }
};

int main() {
  int i = 0;
  MyClass<int&> m2(i, by_ref);
}

--------------------------

gcc ignores the ByRef tag, and picks constructor 1, and then fails to
compile because of the resulting reference to a reference.

Without the -std=c++98 option, gcc-4.3 onwards pick the right overload
(constructor 2), as does Comeau in strict c++03 mode.

Is this a gcc bug or do c++98 overload rules compel the tag
enumeration to be ignored and the incorrect constructor to be called?
If c++98 overload rules compel this behaviour, at what point did it
change (is it a c++03 thing, or in anticipation of c++0x?)

Chris