diff -u b/core/lib/Drupal/Core/Config/FileStorage.php b/core/lib/Drupal/Core/Config/FileStorage.php
--- b/core/lib/Drupal/Core/Config/FileStorage.php
+++ b/core/lib/Drupal/Core/Config/FileStorage.php
@@ -76,6 +76,9 @@
   protected static function getDumper() {
     if (!isset(self::$dumper)) {
       self::$dumper = new Dumper();
+      // Set indentation to 2 spaces to bring it into line with Drupal coding
+      // standards.
+      self::$dumper->setIndentation(2);
     }
     return self::$dumper;
   }
only in patch2:
unchanged:
--- a/core/modules/aggregator/config/aggregator.settings.yml
+++ b/core/modules/aggregator/config/aggregator.settings.yml
@@ -1,11 +1,11 @@
 fetcher: aggregator
 parser: aggregator
 processors:
-    - aggregator
+  - aggregator
 items:
-    allowed_html: '<a> <b> <br> <dd> <dl> <dt> <em> <i> <li> <ol> <p> <strong> <u> <ul>'
-    teaser_length: '600'
-    expire: '9676800'
+  allowed_html: '<a> <b> <br> <dd> <dl> <dt> <em> <i> <li> <ol> <p> <strong> <u> <ul>'
+  teaser_length: '600'
+  expire: '9676800'
 source:
-    list_max: '3'
-    category_selector: checkboxes
+  list_max: '3'
+  category_selector: checkboxes
only in patch2:
unchanged:
--- a/core/modules/contact/config/contact.settings.yml
+++ b/core/modules/contact/config/contact.settings.yml
@@ -1,4 +1,4 @@
 flood:
-    limit: '5'
-    interval: '3600'
+  limit: '5'
+  interval: '3600'
 user_default_enabled: '1'
only in patch2:
unchanged:
--- a/core/modules/forum/config/forum.settings.yml
+++ b/core/modules/forum/config/forum.settings.yml
@@ -1,11 +1,11 @@
 block:
-    active:
-        limit: '5'
-    new:
-        limit: '5'
+  active:
+    limit: '5'
+  new:
+    limit: '5'
 containers: []
 topics:
-    hot_threshold: '15'
-    order: '1'
-    page_limit: '25'
+  hot_threshold: '15'
+  order: '1'
+  page_limit: '25'
 vocabulary: '0'
only in patch2:
unchanged:
--- a/core/modules/image/config/image.style.large.yml
+++ b/core/modules/image/config/image.style.large.yml
@@ -1,10 +1,10 @@
 name: large
 effects:
-    image_scale_480_480_1:
-        name: image_scale
-        data:
-            width: '480'
-            height: '480'
-            upscale: '1'
-        weight: '0'
-        ieid: image_scale_480_480_1
+  image_scale_480_480_1:
+    name: image_scale
+    data:
+      width: '480'
+      height: '480'
+      upscale: '1'
+    weight: '0'
+    ieid: image_scale_480_480_1
only in patch2:
unchanged:
--- a/core/modules/image/config/image.style.medium.yml
+++ b/core/modules/image/config/image.style.medium.yml
@@ -1,10 +1,10 @@
 name: medium
 effects:
-    image_scale_220_220_1:
-        name: image_scale
-        data:
-            width: '220'
-            height: '220'
-            upscale: '1'
-        weight: '0'
-        ieid: image_scale_220_220_1
+  image_scale_220_220_1:
+    name: image_scale
+    data:
+      width: '220'
+      height: '220'
+      upscale: '1'
+    weight: '0'
+    ieid: image_scale_220_220_1
only in patch2:
unchanged:
--- a/core/modules/image/config/image.style.thumbnail.yml
+++ b/core/modules/image/config/image.style.thumbnail.yml
@@ -1,10 +1,10 @@
 name: thumbnail
 effects:
-    image_scale_100_100_1:
-        name: image_scale
-        data:
-            width: '100'
-            height: '100'
-            upscale: '1'
-        weight: '0'
-        ieid: image_scale_100_100_1
+  image_scale_100_100_1:
+    name: image_scale
+    data:
+      width: '100'
+      height: '100'
+      upscale: '1'
+    weight: '0'
+    ieid: image_scale_100_100_1
only in patch2:
unchanged:
--- a/core/modules/search/config/search.settings.yml
+++ b/core/modules/search/config/search.settings.yml
@@ -1,22 +1,22 @@
 active_modules:
-    - node
-    - user
+  - node
+  - user
 and_or_limit: '7'
 default_module: node
 index:
-    cron_limit: '100'
-    overlap_cjk: '1'
-    minimum_word_size: '3'
-    tag_weights:
-        h1: '25'
-        h2: '18'
-        h3: '15'
-        h4: '14'
-        h5: '9'
-        h6: '6'
-        u: '3'
-        b: '3'
-        i: '3'
-        strong: '3'
-        em: '3'
-        a: '10'
+  cron_limit: '100'
+  overlap_cjk: '1'
+  minimum_word_size: '3'
+  tag_weights:
+    h1: '25'
+    h2: '18'
+    h3: '15'
+    h4: '14'
+    h5: '9'
+    h6: '6'
+    u: '3'
+    b: '3'
+    i: '3'
+    strong: '3'
+    em: '3'
+    a: '10'
only in patch2:
unchanged:
--- a/core/modules/system/config/system.cron.yml
+++ b/core/modules/system/config/system.cron.yml
@@ -1,5 +1,5 @@
 key: ''
 threshold:
-    autorun: '10800'
-    requirements_warning: '172800'
-    requirements_error: '1209600'
+  autorun: '10800'
+  requirements_warning: '172800'
+  requirements_error: '1209600'
only in patch2:
unchanged:
--- a/core/modules/system/config/system.rss.yml
+++ b/core/modules/system/config/system.rss.yml
@@ -1,5 +1,5 @@
 channel:
-    description: ''
+  description: ''
 items:
-    limit: '10'
-    view_mode: fulltext
+  limit: '10'
+  view_mode: fulltext
only in patch2:
unchanged:
--- a/core/modules/system/config/system.site.yml
+++ b/core/modules/system/config/system.site.yml
@@ -2,6 +2,6 @@ name: Drupal
 mail: ''
 slogan: ''
 page:
-    403: ''
-    404: ''
-    front: user
+  403: ''
+  404: ''
+  front: user
only in patch2:
unchanged:
--- a/core/modules/system/tests/modules/config_upgrade/config/config_upgrade.test.yml
+++ b/core/modules/system/tests/modules/config_upgrade/config/config_upgrade.test.yml
@@ -1,4 +1,4 @@
 parent:
-    bar: Bar
-    baz: Baz
+  bar: Bar
+  baz: Baz
 foo: Foo
only in patch2:
unchanged:
--- a/core/modules/update/config/update.settings.yml
+++ b/core/modules/update/config/update.settings.yml
@@ -1,10 +1,10 @@
 check:
-    disabled_extensions: '0'
-    interval_days: '1'
+  disabled_extensions: '0'
+  interval_days: '1'
 fetch:
-    url: ''
-    max_attempts: '2'
-    timeout: '5'
+  url: ''
+  max_attempts: '2'
+  timeout: '5'
 notification:
-    emails: []
-    threshold: '0'
+  emails: []
+  threshold: '0'
only in patch2:
unchanged:
--- a/core/vendor/symfony/yaml/Symfony/Component/Yaml/Dumper.php
+++ b/core/vendor/symfony/yaml/Symfony/Component/Yaml/Dumper.php
@@ -19,6 +19,23 @@ namespace Symfony\Component\Yaml;
 class Dumper
 {
     /**
+     * The amount of spaces to use for indentation of nested nodes.
+     *
+     * @var integer
+     */
+    protected $indentation = 4;
+
+    /**
+     * Sets the indentation.
+     *
+     * @param integer $num The amount of spaces to use for intendation of nested nodes.
+     */
+    public function setIndentation($num)
+    {
+        $this->indentation = (int) $num;
+    }
+
+    /**
      * Dumps a PHP value to YAML.
      *
      * @param mixed   $input  The PHP value
@@ -44,7 +61,7 @@ class Dumper
                     $prefix,
                     $isAHash ? Inline::dump($key).':' : '-',
                     $willBeInlined ? ' ' : "\n",
-                    $this->dump($value, $inline - 1, $willBeInlined ? 0 : $indent + 4)
+                    $this->dump($value, $inline - 1, $willBeInlined ? 0 : $indent + $this->indentation)
                 ).($willBeInlined ? "\n" : '');
             }
         }
only in patch2:
unchanged:
--- a/core/vendor/symfony/yaml/Symfony/Component/Yaml/Escaper.php
+++ b/core/vendor/symfony/yaml/Symfony/Component/Yaml/Escaper.php
@@ -25,13 +25,13 @@ class Escaper
     // first to ensure proper escaping because str_replace operates iteratively
     // on the input arrays. This ordering of the characters avoids the use of strtr,
     // which performs more slowly.
-    static private $escapees = array('\\\\', '\\"',
+    private static $escapees = array('\\\\', '\\"',
                                      "\x00",  "\x01",  "\x02",  "\x03",  "\x04",  "\x05",  "\x06",  "\x07",
                                      "\x08",  "\x09",  "\x0a",  "\x0b",  "\x0c",  "\x0d",  "\x0e",  "\x0f",
                                      "\x10",  "\x11",  "\x12",  "\x13",  "\x14",  "\x15",  "\x16",  "\x17",
                                      "\x18",  "\x19",  "\x1a",  "\x1b",  "\x1c",  "\x1d",  "\x1e",  "\x1f",
                                      "\xc2\x85", "\xc2\xa0", "\xe2\x80\xa8", "\xe2\x80\xa9");
-    static private $escaped  = array('\\"', '\\\\',
+    private static $escaped  = array('\\"', '\\\\',
                                      "\\0",   "\\x01", "\\x02", "\\x03", "\\x04", "\\x05", "\\x06", "\\a",
                                      "\\b",   "\\t",   "\\n",   "\\v",   "\\f",   "\\r",   "\\x0e", "\\x0f",
                                      "\\x10", "\\x11", "\\x12", "\\x13", "\\x14", "\\x15", "\\x16", "\\x17",
@@ -45,7 +45,7 @@ class Escaper
      *
      * @return Boolean True if the value would require double quotes.
      */
-    static public function requiresDoubleQuoting($value)
+    public static function requiresDoubleQuoting($value)
     {
         return preg_match('/'.self::REGEX_CHARACTER_TO_ESCAPE.'/u', $value);
     }
@@ -57,7 +57,7 @@ class Escaper
      *
      * @return string The quoted, escaped string
      */
-    static public function escapeWithDoubleQuotes($value)
+    public static function escapeWithDoubleQuotes($value)
     {
         return sprintf('"%s"', str_replace(self::$escapees, self::$escaped, $value));
     }
@@ -69,7 +69,7 @@ class Escaper
      *
      * @return Boolean True if the value would require single quotes.
      */
-    static public function requiresSingleQuoting($value)
+    public static function requiresSingleQuoting($value)
     {
         return preg_match('/[ \s \' " \: \{ \} \[ \] , & \* \# \?] | \A[ - ? | < > = ! % @ ` ]/x', $value);
     }
@@ -81,7 +81,7 @@ class Escaper
      *
      * @return string The quoted, escaped string
      */
-    static public function escapeWithSingleQuotes($value)
+    public static function escapeWithSingleQuotes($value)
     {
         return sprintf("'%s'", str_replace('\'', '\'\'', $value));
     }
only in patch2:
unchanged:
--- a/core/vendor/symfony/yaml/Symfony/Component/Yaml/Inline.php
+++ b/core/vendor/symfony/yaml/Symfony/Component/Yaml/Inline.php
@@ -29,7 +29,7 @@ class Inline
      *
      * @return array A PHP array representing the YAML string
      */
-    static public function parse($value)
+    public static function parse($value)
     {
         $value = trim($value);
 
@@ -75,7 +75,7 @@ class Inline
      *
      * @throws DumpException When trying to dump PHP resource
      */
-    static public function dump($value)
+    public static function dump($value)
     {
         switch (true) {
             case is_resource($value):
@@ -125,7 +125,7 @@ class Inline
      *
      * @return string The YAML string representing the PHP array
      */
-    static private function dumpArray($value)
+    private static function dumpArray($value)
     {
         // array
         $keys = array_keys($value);
@@ -162,7 +162,7 @@ class Inline
      *
      * @throws ParseException When malformed inline YAML string is parsed
      */
-    static public function parseScalar($scalar, $delimiters = null, $stringDelimiters = array('"', "'"), &$i = 0, $evaluate = true)
+    public static function parseScalar($scalar, $delimiters = null, $stringDelimiters = array('"', "'"), &$i = 0, $evaluate = true)
     {
         if (in_array($scalar[$i], $stringDelimiters)) {
             // quoted scalar
@@ -207,7 +207,7 @@ class Inline
      *
      * @throws ParseException When malformed inline YAML string is parsed
      */
-    static private function parseQuotedScalar($scalar, &$i)
+    private static function parseQuotedScalar($scalar, &$i)
     {
         // Only check the current item we're dealing with (for sequences)
         $subject = substr($scalar, $i);
@@ -242,7 +242,7 @@ class Inline
      *
      * @throws ParseException When malformed inline YAML string is parsed
      */
-    static private function parseSequence($sequence, &$i = 0)
+    private static function parseSequence($sequence, &$i = 0)
     {
         $output = array();
         $len = strlen($sequence);
@@ -298,7 +298,7 @@ class Inline
      *
      * @throws ParseException When malformed inline YAML string is parsed
      */
-    static private function parseMapping($mapping, &$i = 0)
+    private static function parseMapping($mapping, &$i = 0)
     {
         $output = array();
         $len = strlen($mapping);
@@ -359,7 +359,7 @@ class Inline
      *
      * @return string A YAML string
      */
-    static private function evaluateScalar($scalar)
+    private static function evaluateScalar($scalar)
     {
         $scalar = trim($scalar);
 
@@ -404,7 +404,7 @@ class Inline
      *
      * @return string The regular expression
      */
-    static private function getTimestampRegex()
+    private static function getTimestampRegex()
     {
         return <<<EOF
         ~^
only in patch2:
unchanged:
--- a/core/vendor/symfony/yaml/Symfony/Component/Yaml/Parser.php
+++ b/core/vendor/symfony/yaml/Symfony/Component/Yaml/Parser.php
@@ -60,6 +60,7 @@ class Parser
         }
 
         $data = array();
+        $context = null;
         while ($this->moveToNextLine()) {
             if ($this->isCurrentLineEmpty()) {
                 continue;
@@ -72,6 +73,11 @@ class Parser
 
             $isRef = $isInPlace = $isProcessed = false;
             if (preg_match('#^\-((?P<leadspaces>\s+)(?P<value>.+?))?\s*$#u', $this->currentLine, $values)) {
+                if ($context && 'mapping' == $context) {
+                    throw new ParseException('You cannot define a sequence item when in a mapping');
+                }
+                $context = 'sequence';
+
                 if (isset($values['value']) && preg_match('#^&(?P<ref>[^ ]+) *(?P<value>.*)#u', $values['value'], $matches)) {
                     $isRef = $matches['ref'];
                     $values['value'] = $matches['value'];
@@ -104,6 +110,11 @@ class Parser
                     }
                 }
             } elseif (preg_match('#^(?P<key>'.Inline::REGEX_QUOTED_STRING.'|[^ \'"\[\{].*?) *\:(\s+(?P<value>.+?))?\s*$#u', $this->currentLine, $values)) {
+                if ($context && 'sequence' == $context) {
+                    throw new ParseException('You cannot define a mapping item when in a sequence');
+                }
+                $context = 'mapping';
+
                 try {
                     $key = Inline::parseScalar($values['key']);
                 } catch (ParseException $e) {
only in patch2:
unchanged:
--- a/core/vendor/symfony/yaml/Symfony/Component/Yaml/Tests/Fixtures/YtsErrorTests.yml
+++ b/core/vendor/symfony/yaml/Symfony/Component/Yaml/Tests/Fixtures/YtsErrorTests.yml
@@ -23,4 +23,3 @@ yaml: |
     secondline: 2
 php: |
   array('foo' => null, 'firstline' => 1, 'secondline' => 2)
-
only in patch2:
unchanged:
--- /dev/null
+++ b/core/vendor/symfony/yaml/Symfony/Component/Yaml/Tests/Fixtures/embededPhp.yml
@@ -0,0 +1 @@
+value: <?php echo 1 + 2 + 3 ?>
only in patch2:
unchanged:
--- a/core/vendor/symfony/yaml/Symfony/Component/Yaml/Tests/ParserTest.php
+++ b/core/vendor/symfony/yaml/Symfony/Component/Yaml/Tests/ParserTest.php
@@ -160,6 +160,31 @@ EOF;
         $this->parser->parse($yaml);
     }
 
+    /**
+     * @expectedException Symfony\Component\Yaml\Exception\ParseException
+     */
+    public function testSequenceInAMapping()
+    {
+        Yaml::parse(<<<EOF
+yaml:
+  hash: me
+  - array stuff
+EOF
+        );
+    }
+
+    /**
+     * @expectedException Symfony\Component\Yaml\Exception\ParseException
+     */
+    public function testMappingInASequence()
+    {
+        Yaml::parse(<<<EOF
+yaml:
+  - array stuff
+  hash: me
+EOF
+        );
+    }
 }
 
 class B
only in patch2:
unchanged:
--- /dev/null
+++ b/core/vendor/symfony/yaml/Symfony/Component/Yaml/Tests/YamlTest.php
@@ -0,0 +1,41 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\Yaml\Tests;
+
+use Symfony\Component\Yaml\Yaml;
+
+class YamlTest extends \PHPUnit_Framework_TestCase
+{
+
+    public function testParseAndDump()
+    {
+        $data = array('lorem' => 'ipsum', 'dolor' => 'sit');
+        $yml = Yaml::dump($data);
+        $parsed = Yaml::parse($yml);
+        $this->assertEquals($data, $parsed);
+
+        $filename = __DIR__.'/Fixtures/index.yml';
+        $contents = file_get_contents($filename);
+        $parsedByFilename = Yaml::parse($filename);
+        $parsedByContents = Yaml::parse($contents);
+        $this->assertEquals($parsedByFilename, $parsedByContents);
+    }
+
+    public function testEmbededPhp()
+    {
+        $filename = __DIR__.'/Fixtures/embededPhp.yml';
+        Yaml::enablePhpParsing();
+        $parsed = Yaml::parse($filename);
+        $this->assertEquals(array('value' => 6), $parsed);
+    }
+
+}
only in patch2:
unchanged:
--- a/core/vendor/symfony/yaml/Symfony/Component/Yaml/Unescaper.php
+++ b/core/vendor/symfony/yaml/Symfony/Component/Yaml/Unescaper.php
@@ -48,7 +48,7 @@ class Unescaper
     public function unescapeDoubleQuotedString($value)
     {
         $self = $this;
-        $callback = function($match) use($self) {
+        $callback = function($match) use ($self) {
             return $self->unescapeCharacter($match[0]);
         };
 
only in patch2:
unchanged:
--- a/core/vendor/symfony/yaml/Symfony/Component/Yaml/Yaml.php
+++ b/core/vendor/symfony/yaml/Symfony/Component/Yaml/Yaml.php
@@ -22,9 +22,9 @@ use Symfony\Component\Yaml\Exception\ParseException;
  */
 class Yaml
 {
-    static public $enablePhpParsing = false;
+    public static $enablePhpParsing = false;
 
-    static public function enablePhpParsing()
+    public static function enablePhpParsing()
     {
         self::$enablePhpParsing = true;
     }
@@ -49,7 +49,7 @@ class Yaml
      *
      * @api
      */
-    static public function parse($input)
+    public static function parse($input)
     {
         // if input is a file, process it
         $file = '';
@@ -97,14 +97,16 @@ class Yaml
      *
      * @param array   $array  PHP array
      * @param integer $inline The level where you switch to inline YAML
+     * @param integer $indent The amount of spaces to use for indentation of nested nodes.
      *
      * @return string A YAML string representing the original PHP array
      *
      * @api
      */
-    static public function dump($array, $inline = 2)
+    public static function dump($array, $inline = 2, $indent = 4)
     {
         $yaml = new Dumper();
+        $yaml->setIndentation($indent);
 
         return $yaml->dump($array, $inline);
     }