Merge branch '3.4' into 4.0

* 3.4:
  [Translation] Process multiple segments within a single unit.
  Document the container.autowiring.strict_mode option
  fix custom radios/inputs for checkbox/radio type
  Another PR template tweak
  [FrameworkBundle] Add missing XML config for circular_reference_handler. Add tests.
  fix CS
  [PropertyInfo] ReflectionExtractor: give a chance to other extractors if no properties
  Clean calls to http_build_query()
  [WebProfilerBundle] limit ajax request to 100 and remove the last one
  Add support for URL-like DSNs for the PdoSessionHandler
  [HttpFoundation] Fix missing "throw" in JsonResponse
  Improve the documentation of
  Suppress warning from sapi_windows_vt100_support on stream other than STDIO
  removed extra-verbose comments
  Fixes #26136: Avoid emitting warning in hasParameterOption()
  Added a README entry to the PR template
  [HttpFoundation] Add x-zip-compressed to MimeTypeExtensionGuesser.
  [DI] Add null check for removeChild

Author: nicolas-grekas

Filesystem.php

@@ -524,13 +524,18 @@ public function makePathRelative($endPath, $startPath)
     /**
      * Mirrors a directory to another.
      *
+     * Copies files and directories from the origin directory into the target directory. By default:
+     *
+     *  - existing files in the target directory will be overwritten, except if they are newer (see the `override` option)
+     *  - files in the target directory that do not exist in the source directory will not be deleted (see the `delete` option)
+     *
      * @param string       $originDir The origin directory
      * @param string       $targetDir The target directory
-     * @param \Traversable $iterator  A Traversable instance
+     * @param \Traversable $iterator  Iterator that filters which files and directories to copy
      * @param array        $options   An array of boolean options
      *                                Valid options are:
-     *                                - $options['override'] Whether to override an existing file on copy or not (see copy())
-     *                                - $options['copy_on_windows'] Whether to copy files instead of links on Windows (see symlink())
+     *                                - $options['override'] If true, target files newer than origin files are overwritten (see copy(), defaults to false)
+     *                                - $options['copy_on_windows'] Whether to copy files instead of links on Windows (see symlink(), defaults to false)
      *                                - $options['delete'] Whether to delete files that are not in the source directory (defaults to false)
      *
      * @throws IOException When file type is unknown