Restore Python 2.6.<6 compatibility (Fixes #1860)

youtube_dl/utils.py

@@ -547,7 +547,7 @@ def __init__(self, *args, **kwargs):
 
             def connect(self):
                 sock = socket.create_connection((self.host, self.port), self.timeout)
-                if self._tunnel_host:
+                if getattr(self, '_tunnel_host', False):
                     self.sock = sock
                     self._tunnel()
                 try: