Issue #28022: Deprecate ssl-related arguments in favor of SSLContext.

The deprecation include manual creation of SSLSocket and certfile/keyfile
(or similar) in ftplib, httplib, imaplib, smtplib, poplib and urllib.

ssl.wrap_socket() is not marked as deprecated yet.

Lib/urllib/request.py

@@ -198,6 +198,9 @@ def urlopen(url, data=None, timeout=socket._GLOBAL_DEFAULT_TIMEOUT,
     '''
     global _opener
     if cafile or capath or cadefault:
+        import warnings
+        warnings.warn("cafile, cpath and cadefault are deprecated, use a "
+                      "custom context instead.", DeprecationWarning, 2)
         if context is not None:
             raise ValueError(
                 "You can't pass both context and any of cafile, capath, and "