auto ref escaping local variable

[Robert burner Schadek via Digitalmars-d]

I have this program that used to compile with 72 but with 73 dmd 
is complaining that
"Error: escaping reference to local variable t"
auto ref f2(T)(auto ref T t, auto ref T s) {
        return t;
}

auto ref f1(T)(auto ref T t, auto ref T s) {
        return f2(t, s);
}

unittest {
        int a = f1(1,2);
}

I'm not sure why, or how to fix that.

https://issues.dlang.org/show_bug.cgi?id=17117