Merge branch '4.4'

* 4.4:
  Update GitHub PR template
  [DI] fix related to preloading
  [HttpKernel] fix compat with legacy DebugClassLoader
  [WebProfilerBundle] Assign automatic colors to custom Stopwatch categories
  [DI] use dirname() when possible
  Simplify usage of dirname()
  Remove Google references when not needed
  Simplify usage of dirname()
  don't dump a scalar tag value on its own line
  Remove Google references when not needed
  [DI] fix Preloader
  [HttpClient] fix calling the buffer-enabling callback
  [HttpClient] fix php notice on push
  do not perform string operations on null
  Require exact match when reading from stdin with a dash

Author: nicolas-grekas

DeprecationErrorHandler/Deprecation.php

@@ -267,7 +267,7 @@ private static function getVendors()
             foreach (get_declared_classes() as $class) {
                 if ('C' === $class[0] && 0 === strpos($class, 'ComposerAutoloaderInit')) {
                     $r = new \ReflectionClass($class);
-                    $v = \dirname(\dirname($r->getFileName()));
+                    $v = \dirname($r->getFileName(), 2);
                     if (file_exists($v.'/composer/installed.json')) {
                         self::$vendors[] = $v;
                         $loader = require $v.'/autoload.php';