diff --git a/.github/PULL_REQUEST_TEMPLATE.md b/.github/PULL_REQUEST_TEMPLATE.md
index e51cf88761..2d64894f41 100644
--- a/.github/PULL_REQUEST_TEMPLATE.md
+++ b/.github/PULL_REQUEST_TEMPLATE.md
@@ -3,16 +3,18 @@
 | Branch?       | master for features / 2.7 up to 4.0 for bug fixes <!-- see below -->
 | Bug fix?      | yes/no
 | New feature?  | yes/no <!-- don't forget to update src/**/CHANGELOG.md files -->
-| BC breaks?    | yes/no
+| BC breaks?    | no     <!-- see https://symfony.com/bc -->
 | Deprecations? | yes/no <!-- don't forget to update UPGRADE-*.md files -->
-| Tests pass?   | yes/no
-| Fixed tickets | #... <!-- #-prefixed issue number(s), if any -->
+| Tests pass?   | yes    <!-- please add some, will be required by reviewers -->
+| Fixed tickets | #...   <!-- #-prefixed issue number(s), if any -->
 | License       | MIT
-| Doc PR        | symfony/symfony-docs#... <!--highly recommended for new features-->
+| Doc PR        | symfony/symfony-docs#... <!-- required for new features -->
 
 <!--
-- Bug fixes must be submitted against the lowest branch where they apply
-  (lowest branches are regularly merged to upper ones so they get the fixes too).
-- Features and deprecations must be submitted against the master branch.
-- Replace this comment by a description of what your PR is solving.
+Write a short README entry for your feature/bugfix here (replace this comment block.)
+This will help people understand your PR and can be used as a start of the Doc PR.
+Additionally:
+ - Bug fixes must be submitted against the lowest branch where they apply
+   (lowest branches are regularly merged to upper ones so they get the fixes too).
+ - Features and deprecations must be submitted against the master branch.
 -->
diff --git a/src/Symfony/Component/Console/Input/ArgvInput.php b/src/Symfony/Component/Console/Input/ArgvInput.php
index 6bcfcf4a90..fd81981070 100644
--- a/src/Symfony/Component/Console/Input/ArgvInput.php
+++ b/src/Symfony/Component/Console/Input/ArgvInput.php
@@ -286,7 +286,7 @@ class ArgvInput extends Input
                 //   For long options, test for '--option=' at beginning
                 //   For short options, test for '-o' at beginning
                 $leading = 0 === strpos($value, '--') ? $value.'=' : $value;
-                if ($token === $value || 0 === strpos($token, $leading)) {
+                if ($token === $value || '' !== $leading && 0 === strpos($token, $leading)) {
                     return true;
                 }
             }
@@ -317,7 +317,7 @@ class ArgvInput extends Input
                 //   For long options, test for '--option=' at beginning
                 //   For short options, test for '-o' at beginning
                 $leading = 0 === strpos($value, '--') ? $value.'=' : $value;
-                if (0 === strpos($token, $leading)) {
+                if ('' !== $leading && 0 === strpos($token, $leading)) {
                     return substr($token, strlen($leading));
                 }
             }
diff --git a/src/Symfony/Component/Console/Output/StreamOutput.php b/src/Symfony/Component/Console/Output/StreamOutput.php
index d9e6bd119f..324323be27 100644
--- a/src/Symfony/Component/Console/Output/StreamOutput.php
+++ b/src/Symfony/Component/Console/Output/StreamOutput.php
@@ -92,7 +92,7 @@ class StreamOutput extends Output
     {
         if (DIRECTORY_SEPARATOR === '\\') {
             return
-                function_exists('sapi_windows_vt100_support') && sapi_windows_vt100_support($this->stream)
+                function_exists('sapi_windows_vt100_support') && @sapi_windows_vt100_support($this->stream)
                 || '10.0.10586' === PHP_WINDOWS_VERSION_MAJOR.'.'.PHP_WINDOWS_VERSION_MINOR.'.'.PHP_WINDOWS_VERSION_BUILD
                 || false !== getenv('ANSICON')
                 || 'ON' === getenv('ConEmuANSI')
diff --git a/src/Symfony/Component/Console/Tests/Input/ArgvInputTest.php b/src/Symfony/Component/Console/Tests/Input/ArgvInputTest.php
index 8febf4875b..61d1723e08 100644
--- a/src/Symfony/Component/Console/Tests/Input/ArgvInputTest.php
+++ b/src/Symfony/Component/Console/Tests/Input/ArgvInputTest.php
@@ -370,6 +370,19 @@ class ArgvInputTest extends TestCase
         $this->assertFalse($input->hasParameterOption('-fh'), '->hasParameterOption() returns true if the given short option is in the raw input');
     }
 
+    public function testNoWarningOnInvalidParameterOption()
+    {
+        $input = new ArgvInput(array('cli.php', '-edev'));
+
+        $this->assertTrue($input->hasParameterOption(array('-e', '')));
+        // No warning thrown
+        $this->assertFalse($input->hasParameterOption(array('-m', '')));
+
+        $this->assertEquals('dev', $input->getParameterOption(array('-e', '')));
+        // No warning thrown
+        $this->assertFalse($input->getParameterOption(array('-m', '')));
+    }
+
     public function testToString()
     {
         $input = new ArgvInput(array('cli.php', '-f', 'foo'));
diff --git a/src/Symfony/Component/DomCrawler/Form.php b/src/Symfony/Component/DomCrawler/Form.php
index 8eaae3e389..19b8c3a931 100644
--- a/src/Symfony/Component/DomCrawler/Form.php
+++ b/src/Symfony/Component/DomCrawler/Form.php
@@ -209,7 +209,7 @@ class Form extends Link implements \ArrayAccess
                 parse_str($query, $currentParameters);
             }
 
-            $queryString = http_build_query(array_merge($currentParameters, $this->getValues()), null, '&');
+            $queryString = http_build_query(array_merge($currentParameters, $this->getValues()), '', '&');
 
             $pos = strpos($uri, '?');
             $base = false === $pos ? $uri : substr($uri, 0, $pos);
diff --git a/src/Symfony/Component/Filesystem/Filesystem.php b/src/Symfony/Component/Filesystem/Filesystem.php
index 554bf22694..50d7dcb4af 100644
--- a/src/Symfony/Component/Filesystem/Filesystem.php
+++ b/src/Symfony/Component/Filesystem/Filesystem.php
@@ -519,13 +519,18 @@ class Filesystem
     /**
      * 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
diff --git a/src/Symfony/Component/HttpFoundation/File/MimeType/MimeTypeExtensionGuesser.php b/src/Symfony/Component/HttpFoundation/File/MimeType/MimeTypeExtensionGuesser.php
index 896c135a53..77bf51b1e5 100644
--- a/src/Symfony/Component/HttpFoundation/File/MimeType/MimeTypeExtensionGuesser.php
+++ b/src/Symfony/Component/HttpFoundation/File/MimeType/MimeTypeExtensionGuesser.php
@@ -599,6 +599,7 @@ class MimeTypeExtensionGuesser implements ExtensionGuesserInterface
         'application/x-xliff+xml' => 'xlf',
         'application/x-xpinstall' => 'xpi',
         'application/x-xz' => 'xz',
+        'application/x-zip-compressed' => 'zip',
         'application/x-zmachine' => 'z1',
         'application/xaml+xml' => 'xaml',
         'application/xcap-diff+xml' => 'xdf',
diff --git a/src/Symfony/Component/HttpFoundation/Request.php b/src/Symfony/Component/HttpFoundation/Request.php
index 42c1a6556c..164fb4e0e3 100644
--- a/src/Symfony/Component/HttpFoundation/Request.php
+++ b/src/Symfony/Component/HttpFoundation/Request.php
@@ -557,7 +557,7 @@ class Request
      */
     public function overrideGlobals()
     {
-        $this->server->set('QUERY_STRING', static::normalizeQueryString(http_build_query($this->query->all(), null, '&')));
+        $this->server->set('QUERY_STRING', static::normalizeQueryString(http_build_query($this->query->all(), '', '&')));
 
         $_GET = $this->query->all();
         $_POST = $this->request->all();
diff --git a/src/Symfony/Component/HttpFoundation/Tests/RequestTest.php b/src/Symfony/Component/HttpFoundation/Tests/RequestTest.php
index 38b61c24a6..230ad15673 100644
--- a/src/Symfony/Component/HttpFoundation/Tests/RequestTest.php
+++ b/src/Symfony/Component/HttpFoundation/Tests/RequestTest.php
@@ -2316,7 +2316,7 @@ class RequestContentProxy extends Request
 {
     public function getContent($asResource = false)
     {
-        return http_build_query(array('_method' => 'PUT', 'content' => 'mycontent'));
+        return http_build_query(array('_method' => 'PUT', 'content' => 'mycontent'), '', '&');
     }
 }
 
diff --git a/src/Symfony/Component/PropertyInfo/Extractor/ReflectionExtractor.php b/src/Symfony/Component/PropertyInfo/Extractor/ReflectionExtractor.php
index 47081b1d77..69ec253b95 100644
--- a/src/Symfony/Component/PropertyInfo/Extractor/ReflectionExtractor.php
+++ b/src/Symfony/Component/PropertyInfo/Extractor/ReflectionExtractor.php
@@ -109,7 +109,7 @@ class ReflectionExtractor implements PropertyListExtractorInterface, PropertyTyp
             $properties[$propertyName] = $propertyName;
         }
 
-        return array_values($properties);
+        return $properties ? array_values($properties) : null;
     }
 
     /**
diff --git a/src/Symfony/Component/PropertyInfo/Tests/Extractors/ReflectionExtractorTest.php b/src/Symfony/Component/PropertyInfo/Tests/Extractors/ReflectionExtractorTest.php
index 02729b4bf9..176e1511f8 100644
--- a/src/Symfony/Component/PropertyInfo/Tests/Extractors/ReflectionExtractorTest.php
+++ b/src/Symfony/Component/PropertyInfo/Tests/Extractors/ReflectionExtractorTest.php
@@ -59,6 +59,8 @@ class ReflectionExtractorTest extends TestCase
             ),
             $this->extractor->getProperties('Symfony\Component\PropertyInfo\Tests\Fixtures\Dummy')
         );
+
+        $this->assertNull($this->extractor->getProperties('Symfony\Component\PropertyInfo\Tests\Fixtures\NoProperties'));
     }
 
     public function testGetPropertiesWithCustomPrefixes()
diff --git a/src/Symfony/Component/PropertyInfo/Tests/Fixtures/NoProperties.php b/src/Symfony/Component/PropertyInfo/Tests/Fixtures/NoProperties.php
new file mode 100644
index 0000000000..177bbe4df0
--- /dev/null
+++ b/src/Symfony/Component/PropertyInfo/Tests/Fixtures/NoProperties.php
@@ -0,0 +1,21 @@
+<?php
+
+namespace Symfony\Component\PropertyInfo\Tests\Fixtures;
+
+/*
+ * 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\PropertyInfo\Tests\Fixtures;
+
+/**
+ * @author Kévin Dunglas <dunglas@gmail.com>
+ */
+class NoProperties
+{
+}
diff --git a/src/Symfony/Component/Security/Http/Firewall/SwitchUserListener.php b/src/Symfony/Component/Security/Http/Firewall/SwitchUserListener.php
index 0a0f334413..c062e9667c 100644
--- a/src/Symfony/Component/Security/Http/Firewall/SwitchUserListener.php
+++ b/src/Symfony/Component/Security/Http/Firewall/SwitchUserListener.php
@@ -95,7 +95,7 @@ class SwitchUserListener implements ListenerInterface
 
         if (!$this->stateless) {
             $request->query->remove($this->usernameParameter);
-            $request->server->set('QUERY_STRING', http_build_query($request->query->all()));
+            $request->server->set('QUERY_STRING', http_build_query($request->query->all(), '', '&'));
             $response = new RedirectResponse($request->getUri(), 302);
 
             $event->setResponse($response);
diff --git a/src/Symfony/Component/Security/Http/Logout/LogoutUrlGenerator.php b/src/Symfony/Component/Security/Http/Logout/LogoutUrlGenerator.php
index 503ceb7f37..788f6470f9 100644
--- a/src/Symfony/Component/Security/Http/Logout/LogoutUrlGenerator.php
+++ b/src/Symfony/Component/Security/Http/Logout/LogoutUrlGenerator.php
@@ -127,7 +127,7 @@ class LogoutUrlGenerator
             $url = UrlGeneratorInterface::ABSOLUTE_URL === $referenceType ? $request->getUriForPath($logoutPath) : $request->getBaseUrl().$logoutPath;
 
             if (!empty($parameters)) {
-                $url .= '?'.http_build_query($parameters);
+                $url .= '?'.http_build_query($parameters, '', '&');
             }
         } else {
             if (!$this->router) {