undeprecate the single-colon notation for controllers

src/Symfony/Bundle/FrameworkBundle/Routing/DelegatingLoader.php

@@ -95,7 +95,7 @@ class DelegatingLoader extends BaseDelegatingLoader
 
             if (1 === substr_count($controller, ':')) {
                 $nonDeprecatedNotation = str_replace(':', '::', $controller);
-                @trigger_error(sprintf('Referencing controllers with a single colon is deprecated since Symfony 4.1, use "%s" instead.', $nonDeprecatedNotation), E_USER_DEPRECATED);
+                // TODO deprecate this in 5.1
             }
 
             $route->setDefault('_controller', $controller);

src/Symfony/Bundle/FrameworkBundle/Tests/Routing/DelegatingLoaderTest.php

@@ -25,7 +25,6 @@ class DelegatingLoaderTest extends TestCase
     /**
      * @group legacy
      * @expectedDeprecation Referencing controllers with foo:bar:baz is deprecated since Symfony 4.1, use "some_parsed::controller" instead.
-     * @expectedDeprecation Referencing controllers with a single colon is deprecated since Symfony 4.1, use "foo::baz" instead.
      */
     public function testLoad()
     {