Spurious "undefined identifier 'T'" when pattern-matching instantiation of fully qualified template

[VPanteleev-S7]

static import std.typecons;
import std.typecons : Nullable;

void a(T)(Nullable!T) {}
void b(T)(std.typecons.Nullable!T) {}

unittest
{
	Nullable!int i;
	a(i); // OK
	b(i); // Error: undefined identifier `T`
}

[baz-bg]

reduced in a single module:

module m21008;

struct Nullable(T){}

void a(T)(Nullable!T) {}
void b(T)(m21008.Nullable!T) {}
void c(T)(.Nullable!T) {}

unittest
{
    Nullable!int i;
    a(i); // OK
    b(i); // Error: undefined identifier `T`
    c(i); // Error: undefined identifier `T`
}  

so hopefully that's only a IFTI bug, not related to imports.