bug #5000 Fixed case where service definition is actually an alias (Xavier Coureau)

This PR was merged into the 2.3 branch.

Discussion
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Fixed case where service definition is actually an alias

If `acme_mailer.transport_chain` service would be an alias, the `hasDefinition` method would return `false` and would fake the expected result.
Same for the further call on `getDefinition` method.

Commits
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c9caef6 Fixed case where definition service is an alias

Author: weaverryan

components/dependency_injection/tags.rst

@@ -133,11 +133,11 @@ custom tag::
     {
         public function process(ContainerBuilder $container)
         {
-            if (!$container->hasDefinition('acme_mailer.transport_chain')) {
+            if (!$container->has('acme_mailer.transport_chain')) {
                 return;
             }
 
-            $definition = $container->getDefinition(
+            $definition = $container->findDefinition(
                 'acme_mailer.transport_chain'
             );