Merge branch '6.1' into 6.2

* 6.1:
  parse unquoted digits in tag values as integers
  do not wire the MercureTransportFactory if the MercureBundle is not enabled
  skip tests if the signal to be sent is not available
  skip a test if the signal to be sent is not available

Author: derrabus

Tests/ApplicationTest.php

@@ -1961,6 +1961,10 @@ public function testSignalSubscriber()
      */
     public function testSetSignalsToDispatchEvent()
     {
+        if (!\defined('SIGUSR1')) {
+            $this->markTestSkipped('SIGUSR1 not available');
+        }
+
         $command = new BaseSignableCommand();
 
         $subscriber = new SignalEventSubscriber();
@@ -1993,6 +1997,10 @@ public function testSignalableCommandInterfaceWithoutSignals()
 
     public function testSignalableCommandHandlerCalledAfterEventListener()
     {
+        if (!\defined('SIGUSR1')) {
+            $this->markTestSkipped('SIGUSR1 not available');
+        }
+
         $command = new SignableCommand();
 
         $subscriber = new SignalEventSubscriber();