Merge branch '3.4' into 4.0

* 3.4:
  [YAML] Issue #26065: leading spaces in YAML multi-line string literals
  [Bridge\PhpUnit] Exit as late as possible
  [Bridge\PhpUnit] Cleanup BC layer
  [PhpBridge] add PHPUnit 7 support to SymfonyTestsListener
  [Lock] Log already-locked errors as "notice" instead of "warning"
  add context to serialize and deserialize
  Update Repository Symlink Helper
  Document explicitly that dotfiles and vcs files are ignored by default
  [HttpKernel] don't try to wire Request argument with controller.service_arguments
  Make kernel build time optionally deterministic
  Use 0 for unlimited expiry
  [Routing] fix typo
  Bump default PHPUnit version from 6.3 to 6.5
  do not mock the container builder in tests
  [Cache][WebProfiler] fix collecting cache stats with sub-requests + allow clearing calls

Author: nicolas-grekas

Finder.php

@@ -313,6 +313,8 @@ public function exclude($dirs)
     /**
      * Excludes "hidden" directories and files (starting with a dot).
      *
+     * This option is enabled by default.
+     *
      * @param bool $ignoreDotFiles Whether to exclude "hidden" files or not
      *
      * @return $this
@@ -333,6 +335,8 @@ public function ignoreDotFiles($ignoreDotFiles)
     /**
      * Forces the finder to ignore version control directories.
      *
+     * This option is enabled by default.
+     *
      * @param bool $ignoreVCS Whether to exclude VCS files or not
      *
      * @return $this