http://en.wikipedia.org/wiki/Isner%E2%80%93Mahut_match_at_the_2010_Wimbledon_Championships
So the longest ever tennis match broke the scoreboard on court at 47-47 and broke the website at 50-50.
At least with the millennium bug it was about the date being stored in two digits.
What excuse was there here and how common is it for programs to be unprepared for the perfect storm, even to the point of being unnecessarily restricted like this ?
To be prepared for every perfect storm, also unlikely ones, means time.
Usually you have to care about exceptional situations that may occur for some believable reason but I don't think you should really cover every possibility also the one that may occur 1 per 10000 games. Then it depends on what we are talking about..
A Wimbledon scoreboard is not a shuttle launched into the space, it's just something that it is acceptable not to handle very exceptional situations, since it doesn't really create such big problems if one day a match lasts 11 hours and score goes over a specific bound: on a space mission you have to care about also events that may occur 0.001% of the time, on a tennis scoreboard you just don't care..