After discussing it with a number of users I've decided to revert the change...

After discussing it with a number of users I've decided to revert the change to [name!=value]. It is now equal to :not([attr!=value]). Attempting to switch it to [attr]:not([attr!=value]) produced some really non-obvious results and confused users. Fixes jQuery bug #3884.

src/selector.js

@@ -564,7 +564,7 @@ var Expr = Sizzle.selectors = {
 		ATTR: function(elem, match){
 			var result = Expr.attrHandle[ match[1] ] ? Expr.attrHandle[ match[1] ]( elem ) : elem[ match[1] ] || elem.getAttribute( match[1] ), value = result + "", type = match[2], check = match[4];
 			return result == null ?
-				false :
+				type === "!=" :
 				type === "=" ?
 				value === check :
 				type === "*=" ?

test/unit/selector.js

@@ -205,7 +205,7 @@ test("child and adjacent", function() {
 });
 
 test("attributes", function() {
-	expect(34);
+	expect(35);
 	t( "Attribute Exists", "a[title]", ["google"] );
 	t( "Attribute Exists", "*[title]", ["google"] );
 	t( "Attribute Exists", "[title]", ["google"] );
@@ -247,6 +247,7 @@ test("attributes", function() {
 	t( "Attribute Begins With", "a[href ^= 'http://www']", ["google","yahoo"] );
 	t( "Attribute Ends With", "a[href $= 'org/']", ["mark"] );
 	t( "Attribute Contains", "a[href *= 'google']", ["google","groups"] );
+	t( "Attribute Is Not Equal", "#ap a[hreflang!='en']", ["google","groups","anchor1"] );
 	
 	t("Select options via :selected", "#select1 option:selected", ["option1a"] );
 	t("Select options via :selected", "#select2 option:selected", ["option2d"] );