Preserve user agent on redirect

Closes gh-46

@@ -23,7 +23,7 @@
 
 
 // Automatically set on build
-NSString *ASIHTTPRequestVersion = @"v1.6.2-20 2010-06-17";
+NSString *ASIHTTPRequestVersion = @"v1.6.2-21 2010-06-17";
 
 NSString* const NetworkRequestErrorDomain = @"ASIHTTPRequestErrorDomain";
 
@@ -1736,7 +1736,14 @@ static BOOL isiPhoneOS2;
 				[self setRequestMethod:@"GET"];
 				[self setPostBody:nil];
 				[self setPostLength:0];
-				[self setRequestHeaders:nil];
+
+				// Perhaps there are other headers we should be preserving, but it's hard to know what we need to keep and what to throw away.
+				NSString *userAgent = [[self requestHeaders] objectForKey:@"User-Agent"];
+				if (userAgent) {
+					[self setRequestHeaders:[NSMutableDictionary dictionaryWithObject:userAgent forKey:@"User-Agent"]];
+				} else {
+					[self setRequestHeaders:nil];
+				}
 				[self setHaveBuiltRequestHeaders:NO];
 			} else {
 			

@@ -447,6 +447,13 @@
 	
 	success = ([[[request originalURL] absoluteString] isEqualToString:@"http://allseeing-i.com/ASIHTTPRequest/tests/redirect/301"]);
 	GHAssertTrue(success,@"Failed to preserve original url");	
+
+	// Ensure user agent is preserved
+	request = [ASIHTTPRequest requestWithURL:[NSURL URLWithString:@"http://allseeing-i.com/ASIHTTPRequest/tests/redirect/301"]];
+	[request addRequestHeader:@"User-Agent" value:@"test"];
+	[request startSynchronous];
+	success = ([[[request requestHeaders] objectForKey:@"User-Agent"] isEqualToString:@"test"]);
+	GHAssertTrue(success,@"Failed to preserve original user agent on redirect");
 }
 
 // Using a persistent connection for HTTP 305-307 would cause crashes on the redirect, not really sure why
@@ -1604,5 +1611,6 @@
 }
 
 
+
 @synthesize responseData;
 @end
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