Issue 4313 - hg review shouldn't fail if the repository has no URL configured

hgreview.py

 import BaseHTTPServer
 import os
 import re
 import socket
 import sys
 import urllib
 
 from mercurial import cmdutil, error
 
 SERVER = 'https://codereview.adblockplus.org'
@@ skipping 47 matching lines @@
         if not opts.get('title') and opts.get('change'):
             opts['title'] = repo[opts['change']].description()
         if not opts.get('title'):
             opts['title'] = ui.prompt('New review title: ', '')
         if not opts['title'].strip():
             raise error.Abort('No review title given.')
 
         if not opts.get('message'):
             opts['message'] = opts['title']
 
-        path = ui.config('paths', 'default-push') or ui.config('paths', 'default')
+        path = (ui.config('paths', 'default-push')
+                or ui.config('paths', 'default')
+                or '')
         match = re.search(r'^(?:https://|ssh://hg@)(.*)', path)
         if match:
             opts['message'] = '{0}\n\nRepository: {1}'.format(
                 opts['message'].strip(),
                 match.group(1)
             )
 
         # Make sure there is at least one reviewer
         if not opts.get('reviewers'):
             opts['reviewers'] = ui.prompt('Reviewers (comma-separated): ', '')
@@ skipping 70 matching lines @@
   </body>
 </html>
 ''' % port
 
     # Run the upload tool
     issue, patchset = scope['RealMain']([upload_path] + args)
 
     # Wait for the page to check in and retrieve issue URL
     if server:
         server.handle_request()