OK, I've now got some C code with a wrong answer.  I'll send-pr
this later unless someone tells me it is obviously off the wall.

	#include <math.h>
	#include <stdio.h>
	#include <stdlib.h>

	int
	main()
	{
		printf("%.15f\n", atan2(1, 1.2));
		exit(0);
	}

This code produces:

0.785398163397448 on 1.3_ALPHA with the broken library
0.694738276196703 on 1.1

Regards,

Giles