Merge branch '4.4' into 5.2

* 4.4:
  Backport psr/container 1.1/2.0 compatibility
  Bump Symfony version to 4.4.21
  Update VERSION for 4.4.20
  Update CONTRIBUTORS for 4.4.20
  Update CHANGELOG for 4.4.20

Author: derrabus

Compiler/AutowirePass.php

@@ -146,7 +146,7 @@ private function autowireCalls(\ReflectionClass $reflectionClass, bool $isRoot):
         $this->decoratedClass = null;
         $this->getPreviousValue = null;
 
-        if ($isRoot && ($definition = $this->container->getDefinition($this->currentId)) && $this->container->has($this->decoratedId = $definition->innerServiceId)) {
+        if ($isRoot && ($definition = $this->container->getDefinition($this->currentId)) && null !== ($this->decoratedId = $definition->innerServiceId) && $this->container->has($this->decoratedId)) {
             $this->decoratedClass = $this->container->findDefinition($this->decoratedId)->getClass();
         }