Merge pull request #2948 from jakoch/patch-2

disable these xdebug settings only, if xdebug is loaded

src/Composer/Console/Application.php

@@ -56,11 +56,11 @@ class Application extends BaseApplication
 
     public function __construct()
     {
-        if (function_exists('ini_set')) {
+        if (function_exists('ini_set') && extension_loaded('xdebug')) {
             ini_set('xdebug.show_exception_trace', false);
             ini_set('xdebug.scream', false);
-
         }
+
         if (function_exists('date_default_timezone_set') && function_exists('date_default_timezone_get')) {
             date_default_timezone_set(@date_default_timezone_get());
         }