The bug here seems to me that urllib.urlopen() should not allow a relative file path like the one specified. f='./rel/path/to/file.html
urllib2's behavior seems proper that it is raising an Exception.

According to the RFCs the local files are to be acceessed by:
file://localhost/path/to/file
file:///path/to/file

Both are absolute paths to the file where in the second one localhost is omitted.

Let me see if urllib's urlopen be made a little stricter.