Docs: Replace #NUMBER Trac issue references with trac-NUMBER

This is a version of gh-4993 for the `3.x-stable` branch.

The GitHub UI treats `#NUMBER` as referring to its own issues which is confusing
when in jQuery source it's usually referring to the old deprecated Trac instance
at https://bugs.jquery.com. This change replaces all such Trac references with
`trac-NUMBER`.

A few of the references came with the Sizzle integration and referred to the
Sizzle GitHub bug tracker. Those have been replaced with full links instead.

A new entry describing issue reference conventions has been added to README.

Closes gh-4994
Ref gh-4993
Ref 5d5ea01

Author: mgol

README.md

@@ -14,6 +14,12 @@ In the spirit of open source software development, jQuery always encourages comm
 2. [Core Style Guide](https://contribute.jquery.org/style-guide/js/)
 3. [Writing Code for jQuery Foundation Projects](https://contribute.jquery.org/code/)
 
+### References to issues/PRs
+
+GitHub issues/PRs are usually referenced via `gh-NUMBER`, where `NUMBER` is the numerical ID of the issue/PR. You can find such an issue/PR under `https://github.com/jquery/jquery/issues/NUMBER`.
+
+jQuery has used a different bug tracker - based on Trac - in the past, available under [bugs.jquery.com](https://bugs.jquery.com/). It is being kept in read only mode so that referring to past discussions is possible. When jQuery source references one of those issues, it uses the pattern `trac-NUMBER`, where `NUMBER` is the numerical ID of the issue. You can find such an issue under `https://bugs.jquery.com/ticket/NUMBER`.
+
 
 Environments in which to use jQuery
 --------------------------------------

src/ajax.js

@@ -22,7 +22,7 @@ var
 	rantiCache = /([?&])_=[^&]*/,
 	rheaders = /^(.*?):[ \t]*([^\r\n]*)$/mg,
 
-	// #7653, #8125, #8152: local protocol detection
+	// trac-7653, trac-8125, trac-8152: local protocol detection
 	rlocalProtocol = /^(?:about|app|app-storage|.+-extension|file|res|widget):$/,
 	rnoContent = /^(?:GET|HEAD)$/,
 	rprotocol = /^\/\//,
@@ -45,7 +45,7 @@ var
 	 */
 	transports = {},
 
-	// Avoid comment-prolog char sequence (#10098); must appease lint and evade compression
+	// Avoid comment-prolog char sequence (trac-10098); must appease lint and evade compression
 	allTypes = "*/".concat( "*" ),
 
 	// Anchor tag for parsing the document origin
@@ -116,7 +116,7 @@ function inspectPrefiltersOrTransports( structure, options, originalOptions, jqX
 
 // A special extend for ajax options
 // that takes "flat" options (not to be deep extended)
-// Fixes #9887
+// Fixes trac-9887
 function ajaxExtend( target, src ) {
 	var key, deep,
 		flatOptions = jQuery.ajaxSettings.flatOptions || {};
@@ -527,12 +527,12 @@ jQuery.extend( {
 		deferred.promise( jqXHR );
 
 		// Add protocol if not provided (prefilters might expect it)
-		// Handle falsy url in the settings object (#10093: consistency with old signature)
+		// Handle falsy url in the settings object (trac-10093: consistency with old signature)
 		// We also use the url parameter if available
 		s.url = ( ( url || s.url || location.href ) + "" )
 			.replace( rprotocol, location.protocol + "//" );
 
-		// Alias method option to type as per ticket #12004
+		// Alias method option to type as per ticket trac-12004
 		s.type = options.method || options.type || s.method || s.type;
 
 		// Extract dataTypes list
@@ -575,7 +575,7 @@ jQuery.extend( {
 		}
 
 		// We can fire global events as of now if asked to
-		// Don't fire events if jQuery.event is undefined in an AMD-usage scenario (#15118)
+		// Don't fire events if jQuery.event is undefined in an AMD-usage scenario (trac-15118)
 		fireGlobals = jQuery.event && s.global;
 
 		// Watch for a new set of requests
@@ -604,7 +604,7 @@ jQuery.extend( {
 			if ( s.data && ( s.processData || typeof s.data === "string" ) ) {
 				cacheURL += ( rquery.test( cacheURL ) ? "&" : "?" ) + s.data;
 
-				// #9682: remove data so that it's not used in an eventual retry
+				// trac-9682: remove data so that it's not used in an eventual retry
 				delete s.data;
 			}
 

src/ajax/xhr.js

@@ -18,7 +18,7 @@ var xhrSuccessStatus = {
 		0: 200,
 
 		// Support: IE <=9 only
-		// #1450: sometimes IE returns 1223 when it should be 204
+		// trac-1450: sometimes IE returns 1223 when it should be 204
 		1223: 204
 	},
 	xhrSupported = jQuery.ajaxSettings.xhr();
@@ -90,7 +90,7 @@ jQuery.ajaxTransport( function( options ) {
 								} else {
 									complete(
 
-										// File: protocol always yields status 0; see #8605, #14207
+										// File: protocol always yields status 0; see trac-8605, trac-14207
 										xhr.status,
 										xhr.statusText
 									);
@@ -151,7 +151,7 @@ jQuery.ajaxTransport( function( options ) {
 					xhr.send( options.hasContent && options.data || null );
 				} catch ( e ) {
 
-					// #14683: Only rethrow if this hasn't been notified as an error yet
+					// trac-14683: Only rethrow if this hasn't been notified as an error yet
 					if ( callback ) {
 						throw e;
 					}

src/attributes/prop.js

@@ -62,7 +62,7 @@ jQuery.extend( {
 				// Support: IE <=9 - 11 only
 				// elem.tabIndex doesn't always return the
 				// correct value when it hasn't been explicitly set
-				// Use proper attribute retrieval(#12072)
+				// Use proper attribute retrieval (trac-12072)
 				var tabindex = jQuery.find.attr( elem, "tabindex" );
 
 				if ( tabindex ) {

src/attributes/val.js

@@ -91,7 +91,7 @@ jQuery.extend( {
 					val :
 
 					// Support: IE <=10 - 11 only
-					// option.text throws exceptions (#14686, #14858)
+					// option.text throws exceptions (trac-14686, trac-14858)
 					// Strip and collapse whitespace
 					// https://html.spec.whatwg.org/#strip-and-collapse-whitespace
 					stripAndCollapse( jQuery.text( elem ) );
@@ -118,7 +118,7 @@ jQuery.extend( {
 					option = options[ i ];
 
 					// Support: IE <=9 only
-					// IE8-9 doesn't update selected after form reset (#2551)
+					// IE8-9 doesn't update selected after form reset (trac-2551)
 					if ( ( option.selected || i === index ) &&
 
 							// Don't return options that are disabled or in a disabled optgroup

src/core/camelCase.js

@@ -13,7 +13,7 @@ function fcamelCase( _all, letter ) {
 
 // Convert dashed to camelCase; used by the css and data modules
 // Support: IE <=9 - 11, Edge 12 - 15
-// Microsoft forgot to hump their vendor prefix (#9572)
+// Microsoft forgot to hump their vendor prefix (trac-9572)
 function camelCase( string ) {
 	return string.replace( rmsPrefix, "ms-" ).replace( rdashAlpha, fcamelCase );
 }

src/core/init.js

@@ -14,8 +14,8 @@ define( [
 var rootjQuery,
 
 	// A simple way to check for HTML strings
-	// Prioritize #id over <tag> to avoid XSS via location.hash (#9521)
-	// Strict HTML recognition (#11290: must start with <)
+	// Prioritize #id over <tag> to avoid XSS via location.hash (trac-9521)
+	// Strict HTML recognition (trac-11290: must start with <)
 	// Shortcut simple #id case for speed
 	rquickExpr = /^(?:\s*(<[\w\W]+>)[^>]*|#([\w-]+))$/,
 

src/core/ready-no-deferred.js

@@ -30,7 +30,7 @@ jQuery.extend( {
 	isReady: false,
 
 	// A counter to track how many items to wait for before
-	// the ready event fires. See #6781
+	// the ready event fires. See trac-6781
 	readyWait: 1,
 
 	ready: function( wait ) {

src/core/ready.js

@@ -31,7 +31,7 @@ jQuery.extend( {
 	isReady: false,
 
 	// A counter to track how many items to wait for before
-	// the ready event fires. See #6781
+	// the ready event fires. See trac-6781
 	readyWait: 1,
 
 	// Handle when the DOM is ready

src/css.js

@@ -265,15 +265,15 @@ jQuery.extend( {
 		if ( value !== undefined ) {
 			type = typeof value;
 
-			// Convert "+=" or "-=" to relative numbers (#7345)
+			// Convert "+=" or "-=" to relative numbers (trac-7345)
 			if ( type === "string" && ( ret = rcssNum.exec( value ) ) && ret[ 1 ] ) {
 				value = adjustCSS( elem, name, ret );
 
-				// Fixes bug #9237
+				// Fixes bug trac-9237
 				type = "number";
 			}
 
-			// Make sure that null and NaN values aren't set (#7116)
+			// Make sure that null and NaN values aren't set (trac-7116)
 			if ( value == null || value !== value ) {
 				return;
 			}