Sounds like an oversight on the part of the programmer. If URLs have to stay on one line, then it is easy to program to recognise an URL and automatically alter the line parameters. It would also be v. easy to reset the line length to 'normal' after, but it would require the programmer to think of it. I can quite see that it is an easy thing to miss.

I can't think of any other logical reason for this occurrence - which doesn't mean there isn't one, of course!