Templates with alias param instantiated with null cached by DMD..?

[simendsjo]

I've stumbled upon a strange bug, and I'm not sure what I should 
write in the bug report. Could someone explain what's going on 
here or file the bug for me?

template A(alias T) {
    alias A = T;
}
void main() {
    struct S1 { S1* p; }
    static assert(is(typeof(A!(S1.init.p)) == S1*)); // ok

    pragma(msg, "NULL: ", typeof(A!(null))); // fail: S1*

    struct S2 { S2* p; }
    static assert(is(typeof(A!(S2.init.p)) == S2*)); // fail: S1*
}