Merge branch '4.1'

* 4.1:
  Undeprecate the single-colon notation for controllers
  Command::addOption should allow int in $default
  Update symfony links to https
  [Form] Fixed keeping hash of equal \DateTimeInterface on submit
  [PhpUnitBridge] Fix typo
  [Routing] generate(null) should throw an exception
  [Form] Minor fixes in docs and cs
  [Workflow] Made code simpler
  [Config] Unset key during normalization
  [Form] Fixed empty data for compound date types
  invalidate forms on transformation failures
  [FrameworkBundle] fixed guard event names for transitions
  method buildTransitionBlockerList returns TransitionBlockerList of expected transition
  [FrameworkBundle] fixed guard event names for transitions
  [PropertyAccessor] Fix unable to write to singular property using setter while plural adder/remover exist

Author: nicolas-grekas

Generator/Dumper/PhpGeneratorDumper.php

@@ -113,7 +113,7 @@ public function generate($name, $parameters = array(), $referenceType = self::AB
             ?? $this->context->getParameter('_locale')
             ?: $this->defaultLocale;
 
-        if (null !== $locale) {
+        if (null !== $locale && null !== $name) {
             do {
                 if ((self::$declaredRoutes[$name.'.'.$locale][1]['_canonical_route'] ?? null) === $name) {
                     unset($parameters['_locale']);