Provide a clearer error message when urlopen fails because of an

invalid proxy setting.

Minor change to call of unknown_url; always pass data argument
explicitly since data defaults to None.

PEP 42: Add as a feature that urllib handle proxy setting that contain
only the host and port of the proxy.

pep-0042.txt

@@ -137,12 +137,12 @@ Standard Library
       the form "From: Amazon.com <delivers-news2@amazon.com>" should
       be parsed correctly.
 
-      https://sourceforge.net/bugs/?func=detailbug&bug_id=110678&group_id=5470
+      http://sourceforge.net/bugs/?func=detailbug&bug_id=110678&group_id=5470
 
     - cgi.py's FieldStorage class should be more conservative with
       memory in the face of large binary file uploads.
 
-      https://sourceforge.net/bugs/?func=detailbug&bug_id=110674&group_id=5470
+      http://sourceforge.net/bugs/?func=detailbug&bug_id=110674&group_id=5470
 
       There are two issues here: first, because
       read_lines_to_outerboundary() uses readline() it is possible
@@ -157,6 +157,11 @@ Standard Library
       interface it /might/ be safe to remove it.  OTOH, removing it
       will break code clever and nosy code.
 
+    - urllib should support proxy definitions that contain just the
+      host and port 
+
+      http://sourceforge.net/bugs/?func=detailbug&bug_id=110849&group_id=5470
+
 Tools
 
     - IDLE should reload & recompile modules changed externally.  To