[DependencyInjection] Fix handling of repeated #[Autoconfigure] attributes

Author: nicolas-grekas

src/Symfony/Component/DependencyInjection/Loader/YamlFileLoader.php

@@ -448,8 +448,9 @@ private function parseDefinition(string $id, $service, string $file, array $defa
             return $return ? $alias : $this->container->setAlias($id, $alias);
         }
 
+        $changes = [];
         if (null !== $definition) {
-            // no-op
+            $changes = $definition->getChanges();
         } elseif ($this->isLoadingInstanceof) {
             $definition = new ChildDefinition('');
         } elseif (isset($service['parent'])) {
@@ -472,7 +473,7 @@ private function parseDefinition(string $id, $service, string $file, array $defa
             $definition->setAutoconfigured($defaults['autoconfigure']);
         }
 
-        $definition->setChanges([]);
+        $definition->setChanges($changes);
 
         if (isset($service['class'])) {
             $definition->setClass($service['class']);