Sometimes in tzones GMT+something the calculation below can give negative or time greater than 1000

the fix just checks both cases since timezone cannot add more than a day (or less respectively) or in other terms 1000 swatch beats

case 'B':       /* Swatch Beat a.k.a. Internet Time */
beat =  (((((long)the_time)-(((long)the_time) -
        ((((long)the_time) % 86400) + 3600))) * 10) / 864);

-- the fix --

if (beat < 0) beat += 1000;
if (beat > 999) beat -= 1000;

-- end fix --

sprintf(tmp_buff, "%03d", beat); /* SAFE */
strcat(return_value->value.str.val, tmp_buff);
break;