some errors spotted by pyflakes

gunicorn/app/wsgiapp.py

@@ -5,7 +5,6 @@
 
 import os
 import sys
-import traceback
 
 from gunicorn import util
 from gunicorn.app.base import Application

gunicorn/http/__init__.py

@@ -5,3 +5,5 @@
 
 from gunicorn.http.message import Message, Request
 from gunicorn.http.parser import RequestParser
+
+__all__ = [Message, Request, RequestParser]

gunicorn/http/parser.py

@@ -3,8 +3,6 @@
 # This file is part of gunicorn released under the MIT license. 
 # See the NOTICE for more information.
 
-import socket
-
 from gunicorn.http.message import Request
 from gunicorn.http.unreader import SocketUnreader, IterUnreader
 

gunicorn/http/wsgi.py

@@ -39,9 +39,9 @@ def create(req, sock, client, server, debug=False):
                 sock.send("HTTP/1.1 100 Continue\r\n\r\n")
         elif name == "x-forwarded-for":
             forward = hdr_value
-        elif name == "x-forwarded-protocol" and value.lower() == "ssl":
+        elif name == "x-forwarded-protocol" and hdr_value.lower() == "ssl":
             url_scheme = "https"
-        elif name == "x-forwarded-ssl" and value.lower() == "on":
+        elif name == "x-forwarded-ssl" and hdr_value.lower() == "on":
             url_scheme = "https"
         elif name == "host":
             server = hdr_value