Fixes #7881. Setting contentType to false will prevent the Content-Type header from being sent. Unit test added.

src/ajax.js

@@ -559,7 +559,7 @@ jQuery.extend({
 			}
 
 			// Set the correct header, if data is being sent
-			if ( ( s.data && s.hasContent ) || options.contentType ) {
+			if ( s.data && s.hasContent && s.contentType !== false || options.contentType ) {
 				requestHeaders[ "content-type" ] = s.contentType;
 			}
 

test/data/headers.php

@@ -6,15 +6,11 @@ $headers = array();
 
 foreach( $_SERVER as $key => $value ) {
 
-	if ( substr( $key , 0 , 5 ) == "HTTP_" ) {
+	$key = str_replace( "_" , "-" , substr( $key , 0 , 5 ) == "HTTP_" ? substr( $key , 5 ) : $key );
-
-		$key = str_replace( "_" , "-" , substr( $key , 5) );
 	$headers[ $key ] = $value;
 
 }
 
-}
-
 foreach( explode( "_" , $_GET[ "keys" ] ) as $key ) {
-	echo "$key: " . $headers[ strtoupper( $key ) ] . "\n";
+	echo "$key: " . @$headers[ strtoupper( $key ) ] . "\n";
 }

test/unit/ajax.js

@@ -276,6 +276,42 @@ test(".ajax() - headers" , function() {
 
 });
 
+test(".ajax() - contentType" , function() {
+
+	expect( 2 );
+
+	stop();
+
+	var count = 2;
+
+	function restart() {
+		if ( ! --count ) {
+			start();
+		}
+	}
+
+	jQuery.ajax(url("data/headers.php?keys=content-type" ), {
+		contentType: "test",
+		success: function( data ) {
+			strictEqual( data , "content-type: test\n" , "Test content-type is sent when options.contentType is set" );
+		},
+		complete: function() {
+			restart();
+		}
+	});
+
+	jQuery.ajax(url("data/headers.php?keys=content-type" ), {
+		contentType: false,
+		success: function( data ) {
+			strictEqual( data , "content-type: \n" , "Test content-type is not sent when options.contentType===false" );
+		},
+		complete: function() {
+			restart();
+		}
+	});
+
+});
+
 test(".ajax() - hash", function() {
 	expect(3);