Merge branch '1.x' into 2.x

* 1.x:
  [Bug] Fix Flex not installing recipes while it is being upgraded

Author: fabpot

src/Flex.php

@@ -52,6 +52,8 @@
  */
 class Flex implements PluginInterface, EventSubscriberInterface
 {
+    public static $storedOperations = [];
+
     /**
      * @var Composer
      */
@@ -111,6 +113,13 @@ class_exists(__NAMESPACE__.str_replace('/', '\\', substr($file, \strlen(__DIR__)
         $this->config = $composer->getConfig();
         $this->options = $this->initOptions();
 
+        // if Flex is being upgraded, the original operations from the original Flex
+        // instance are stored in the static property, so we can reuse them now.
+        if (property_exists(self::class, 'storedOperations') && self::$storedOperations) {
+            $this->operations = self::$storedOperations;
+            self::$storedOperations = [];
+        }
+
         $symfonyRequire = preg_replace('/\.x$/', '.x-dev', getenv('SYMFONY_REQUIRE') ?: ($composer->getPackage()->getExtra()['symfony']['require'] ?? ''));
 
         $rfs = Factory::createHttpDownloader($this->io, $this->config);
@@ -201,6 +210,8 @@ class_exists(__NAMESPACE__.str_replace('/', '\\', substr($file, \strlen(__DIR__)
      */
     public function deactivate(Composer $composer, IOInterface $io)
     {
+        // store operations in case Flex is being upgraded
+        self::$storedOperations = $this->operations;
         self::$activated = false;
     }