https: do not inherit httplib.HTTPSConnection that creates unused SSLContext

HTTPSConnection of Python 2.7.9 creates SSLContext in __init__, which involves
a password prompt for decrypting the private key. This means the password was
asked twice, one for unused SSLContext, and next for our ssl function.

Because our httpsconnection replaces connect() method at all, we can simply
drop httplib.HTTPSConnection. Instead, class and instance attributes are copied
from it.

HTTPSConnection of Python 2.7.8 and 2.6.9 seem to have no such problem.

https://hg.python.org/cpython/file/v2.7.9/Lib/httplib.py#l1183

mercurial/url.py

@@ -318,11 +318,18 b' class httphandler(keepalive.HTTPHandler)'
         return keepalive.HTTPHandler._start_transaction(self, h, req)
 
 if has_https:
-    class httpsconnection(httplib.HTTPSConnection):
+    class httpsconnection(httplib.HTTPConnection):
         response_class = keepalive.HTTPResponse
+        default_port = httplib.HTTPS_PORT
         # must be able to send big bundle as stream.
         send = _gen_sendfile(keepalive.safesend)
-        getresponse = keepalive.wrapgetresponse(httplib.HTTPSConnection)
+        getresponse = keepalive.wrapgetresponse(httplib.HTTPConnection)
+
+        def __init__(self, host, port=None, key_file=None, cert_file=None,
+                     *args, **kwargs):
+            httplib.HTTPConnection.__init__(self, host, port, *args, **kwargs)
+            self.key_file = key_file
+            self.cert_file = cert_file
 
         def connect(self):
             self.sock = _create_connection((self.host, self.port))