The docs [1] state that `url should be a string containing a valid URL.` An URL with a space ' ' is not a valid URL as the space must be quoted as %20. The brackets may also cause problems as they are not valid xs:anyURI chars.

I vote for reverting the chances as they break the API. You could improve the docs and emphasize that URLs must be quoted correctly as the module doesn't implement browser magic.

[1] http://docs.python.org/py3k/library/urllib.request.html#urllib.request.Request