Merge branch '2.7' into 2.8

* 2.7:
  [DependencyInjection] fix dumped YAML snytax
  Remove InputOption::VALUE_REQUIRED mode from $default parameter description as InputOption::setDefault() throws an exception only when called in InputOption::VALUE_NONE mode. In practice the $default value could still be accessed in InputOption::VALUE_REQUIRED mode in case InputOption was never set but accessed from InputDefinition::getOption() method
  [Form] Fixed violation mapping if multiple forms are using the same (or part of the same) property path
  [TwigBridge] Symfony 3.1 forward compatibility

Author: fabpot

Command/Command.php

@@ -390,7 +390,7 @@ public function addArgument($name, $mode = null, $description = '', $default = n
      * @param string $shortcut    The shortcut (can be null)
      * @param int    $mode        The option mode: One of the InputOption::VALUE_* constants
      * @param string $description A description text
-     * @param mixed  $default     The default value (must be null for InputOption::VALUE_REQUIRED or InputOption::VALUE_NONE)
+     * @param mixed  $default     The default value (must be null for InputOption::VALUE_NONE)
      *
      * @return Command The current instance
      */

Input/InputOption.php

@@ -39,7 +39,7 @@ class InputOption
      * @param string|array $shortcut    The shortcuts, can be null, a string of shortcuts delimited by | or an array of shortcuts
      * @param int          $mode        The option mode: One of the VALUE_* constants
      * @param string       $description A description text
-     * @param mixed        $default     The default value (must be null for self::VALUE_REQUIRED or self::VALUE_NONE)
+     * @param mixed        $default     The default value (must be null for self::VALUE_NONE)
      *
      * @throws InvalidArgumentException If option mode is invalid or incompatible
      */