Use local variable for out parameter rather than direct use of ivar

src/common/mac/HTTPMultipartUpload.m

 // Copyright (c) 2006, Google Inc.
 // All rights reserved.
 //
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 // notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
@@ skipping 177 matching lines @@
   [req setHTTPBody:postBody];
   [req setHTTPMethod:@"POST"];
 
   [response_ release];
   response_ = nil;
 
   NSData *data = nil;
   if ([[req URL] isFileURL]) {
     [[req HTTPBody] writeToURL:[req URL] options:0 error:error];
   } else {
+    NSURLResponse *response = nil;
     data = [NSURLConnection sendSynchronousRequest:req
-                                 returningResponse:&response_
+                                 returningResponse:&response
                                              error:error];
-    [response_ retain];
+    response_ = (NSHTTPURLResponse *)[response retain];
   }
   [req release];
 
   return data;
 }
 
 //=============================================================================
 - (NSHTTPURLResponse *)response {
   return response_;
 }
 
 @end