Merge branch 'explain-map-concat' of https://github.com/ajpiano/jquery into...

Merge branch 'explain-map-concat' of https://github.com/ajpiano/jquery into ajpiano-explain-map-concat

src/core.js

@@ -739,6 +739,7 @@ jQuery.extend({
 			}
 		}
 
+		// Flatten any nested arrays
 		return ret.concat.apply( [], ret );
 	},