transposed with enforceNotJagged not throwing?

[berni via Digitalmars-d-learn]

I expect this small program to throw an Exception:

import std.stdio;
import std.range;

void main()
{
    auto a = [[1,2],
              [4,5,3]];

    a.transposed!(TransverseOptions.enforceNotJagged).writeln;
}

But it just outputs:

[[1, 4], [2, 5], [3]]

Is it a bug or is it me who's doing something wrong?