Merge branch '3.4' into 4.3

* 3.4:
  [Validator] Allow underscore character "_" in URL username and password
  [SecurityBundle] Passwords are not encoded when algorithm set to \"true\"
  do not validate passwords when the hash is null
  [DI] Fix making the container path-independent when the app is in /app
  Allow copy instead of symlink for ./link script
  [FrameworkBundle] resolve service locators in `debug:*` commands
  bumped Symfony version to 3.4.37
  updated VERSION for 3.4.36
  update CONTRIBUTORS for 3.4.36
  updated CHANGELOG for 3.4.36

Author: xabbuh

DependencyInjection/MainConfiguration.php

@@ -399,7 +399,13 @@ private function addEncodersSection(ArrayNodeDefinition $rootNode)
                         ->performNoDeepMerging()
                         ->beforeNormalization()->ifString()->then(function ($v) { return ['algorithm' => $v]; })->end()
                         ->children()
-                            ->scalarNode('algorithm')->cannotBeEmpty()->end()
+                            ->scalarNode('algorithm')
+                                ->cannotBeEmpty()
+                                ->validate()
+                                    ->ifTrue(function ($v) { return !\is_string($v); })
+                                    ->thenInvalid('You must provide a string value.')
+                                ->end()
+                            ->end()
                             ->scalarNode('hash_algorithm')->info('Name of hashing algorithm for PBKDF2 (i.e. sha256, sha512, etc..) See hash_algos() for a list of supported algorithms.')->defaultValue('sha512')->end()
                             ->scalarNode('key_length')->defaultValue(40)->end()
                             ->booleanNode('ignore_case')->defaultFalse()->end()