Icarus does undef propagation of const multiplies incorrectly

The following module should set the output to constant 4'bxxxx:

module test(y);
  output [3:0] y;
  assign y = 4'b0 * 4'bx;
endmodule

But Icarus Verilog (git a3450bf) is too smart and outputs 4'b0000 instead.

History:
2014-02-27 Reported bug on GitHub
2014-02-25 Fixed in GIT commit ed2e339