Comparing two AliasSeq

[Yuxuan Shui via Digitalmars-d-learn]

In this example:

    import std.range;
    template expandRange(alias R) if (isInputRange!(typeof(R))) {
        static if (R.empty)
            alias expandRange = AliasSeq!();
        else
	    alias expandRange = AliasSeq!(R.front(), 
expandRange!(R.drop(1)));
    }
    ///
    unittest {
        import std.range;
        static assert (is(expandRange!(iota(0,5)): 
AliasSeq!(0,1,2,3,4)));
    }

The static assert fails, why?