gcc vs clang behavior on partial specialization with variadic arguments plus extra argument of same type

The following code:

#include <cstddef>

template <size_t N,
          typename T,
          T first,
          T... rest>
struct A {
};

template<typename T,
         T... args>
struct A<0, T, args...> {
};

int main () {
    A<0, int, 1> a0;
    A<2, int, 1, 2> a2;
    return 0;
}

...does not compile with g++ (version 5.1.0 and 5.3.0) due to:

error: partial specialization is not more specialized than the primary template because it replaces multiple parameters with a pack expansion

...but compiles with clang.

Is it allowed to declare such partial specializations?

Side note: Actually, the specialization is dangerous since A<0, int> fails to compile with both compiler (wrong number of template arguments).