avoid url error exception

[kouml]

Summary

To Avoid falling into url error exception, I changed the order of exceptions.

Related Issues

PR Overview

• This PR requires new unit tests [y/n] (make sure tests are included)
• This PR requires to update the documentation [y/n] (make sure the docs are up-to-date)
• This PR is backwards compatible [y/n]
• This PR changes the current API [y/n] (all API changes need to be approved by fchollet)

in

from urllib.error import URLError, HTTPError
try:
    raise URLError(reason="test")
except URLError as e:
    print("URL_Error")
    pass
except HTTPError as e:
    print("HTTP Error")
    pass
try:
    raise HTTPError(url="example.com", code=200, msg="test", hdrs=None, fp=None)
except URLError as e:
   print("URL_Error")
   pass
except HTTPError as e:
   print("HTTP Error")
   pass

out

URL_Error
URL_Error

I found that this code couldn't catch the HTTPError.
Because URLError is a subclass of HTTPError.

in

issubclass(HTTPError, URLError)

out

True

so, it should be changed order.

[fchollet]

That seems reasonable, thanks for the PR!