Senthil: thx for the pointer. 

I've fixed the problem on distribute side by catching any ValueError returned by urlparse (from 2.6 or 2.7 point of view).

That said, I don't think than catching more invalid URLs in Python 2.7 should be considered as a feature. 

If it's a new feature then we should have an option to explicitly parse IpV6-like URLs and leave the default behavior like it was in 2.6. If not, then it should be considered as a bug fix (meaning that Python now discards more malformed URLs) and should be backported imo.

IOW, I want to discard invalid URLs the same way no matter what the Python version is, because this is not a rule defined by Python, rather by some RFCs at the URL level.