Merge branch '4.2'

* 4.2:
  [HttpFoundation] Check file exists before unlink
  [Console] Fixed #29835: ConfirmationQuestion with default true for answer '0'
  [Cache] PDO-based cache pool table autocreation does not work
  [Translation] Concatenated translation messages
  [Form] ensure compatibility with older PHPUnit mocks
  [Serializer] Docblock about throwing exceptions on serializer
  [Cache] fix used variable name
  [Debug][ErrorHandler] Preserve our error handler when a logger set another one
  [Form] Changed UrlType input type to text when default_protocol is not null
  [Bugfix] MemcachedSessionHandler::close() must close connection
  Always pass $key to NullAdapter->createCacheItem

Author: nicolas-grekas

Tests/Extension/AbstractBootstrap3LayoutTest.php

@@ -2505,13 +2505,29 @@ public function testTimezoneWithPlaceholder()
         );
     }
 
-    public function testUrl()
+    public function testUrlWithDefaultProtocol()
     {
         $url = 'http://www.google.com?foo1=bar1&foo2=bar2';
-        $form = $this->factory->createNamed('name', 'Symfony\Component\Form\Extension\Core\Type\UrlType', $url);
+        $form = $this->factory->createNamed('name', 'Symfony\Component\Form\Extension\Core\Type\UrlType', $url, ['default_protocol' => 'http']);
 
         $this->assertWidgetMatchesXpath($form->createView(), ['attr' => ['class' => 'my&class']],
 '/input
+    [@type="text"]
+    [@name="name"]
+    [@class="my&class form-control"]
+    [@value="http://www.google.com?foo1=bar1&foo2=bar2"]
+    [@inputmode="url"]
+'
+        );
+    }
+
+    public function testUrlWithoutDefaultProtocol()
+    {
+        $url = 'http://www.google.com?foo1=bar1&foo2=bar2';
+        $form = $this->factory->createNamed('name', 'Symfony\Component\Form\Extension\Core\Type\UrlType', $url, ['default_protocol' => null]);
+
+        $this->assertWidgetMatchesXpath($form->createView(), ['attr' => ['class' => 'my&class']],
+            '/input
     [@type="url"]
     [@name="name"]
     [@class="my&class form-control"]