The unexpected Google wide domain check bypass
Windows again. "Let's use a backslash instead of a slash in paths" has to be up there with "NUL-terminated strings" in terms of tiny bad ideas from long ago that are still haunting us.<p>Of course it's not as though Google had a choice at the outset, I'm sure some non-trivial number of web sites magically didn't work (and maybe still don't work) if you insist that <a href="https://www.example.com\works\fine\on\my\pc" rel="nofollow">https://www.example.com\works\fine\on\my\pc</a> doesn't do what the person writing it expects... I think we can blame some early Internet Explorer build for first having this work (I can't see Netscape allowing it) and then it becomes a choice whether to be a purist or sigh and move on once IE gets popular and real people do it.