Fixes #7868. ResponseText is now properly propagated for error callbacks.

src/ajax.js

@@ -464,6 +464,11 @@ jQuery.extend({
 			} else { // if not success, mark it as an error
 
 					error = error || statusText;
+
+					// Set responseText if needed
+					if ( response ) {
+						jXHR.responseText = response;
+					}
 			}
 
 			// Set data for the fake xhr object

src/ajax/xhr.js

@@ -137,8 +137,7 @@ jQuery.ajax.transport( function( s , determineDataType ) {
 											status
 									);
 
-							// Guess response if needed & update datatype accordingly
-							if ( status >= 200 && status < 300 ) {
+							// Guess response & update dataType accordingly
 							response =
 								determineDataType(
 									s,
@@ -146,7 +145,6 @@ jQuery.ajax.transport( function( s , determineDataType ) {
 									xhr.responseText,
 									xhr.responseXML );
 						}
-						}
 
 						// Call complete
 						complete(status,statusText,response,responseHeaders);

test/data/errorWithText.php

@@ -0,0 +1,5 @@
+<?php
+
+header("HTTP/1.0 400 Bad Request");
+
+echo "plain text message";

test/unit/ajax.js

@@ -240,6 +240,23 @@ test("jQuery.ajax() - error callbacks", function() {
 	});
 });
 
+test("jQuery.ajax() - responseText on error", function() {
+
+	expect( 1 );
+
+	stop();
+
+	jQuery.ajax({
+		url: url("data/errorWithText.php"),
+		error: function(xhr) {
+			strictEqual( xhr.responseText , "plain text message" , "Test jXHR.responseText is filled for HTTP errors" );
+		},
+		complete: function() {
+			start();
+		}
+	});
+});
+
 test(".ajax() - headers" , function() {
 
 	expect( 2 );