Merge branch 'hotfix/3645' into develop

Forward port zendframework/zendframework#3645

src/Protocol/Smtp.php

@@ -376,10 +376,18 @@ public function auth()
      */
     public function disconnect()
     {
-        $this->quit();
         $this->_disconnect();
     }
 
+    /**
+     * Disconnect from remote host and free resource
+     */
+    protected function _disconnect()
+    {
+        // Make sure the session gets closed
+        $this->quit();
+        parent::_disconnect();
+    }
 
     /**
      * Start mail session

test/Protocol/SmtpTest.php

@@ -60,4 +60,10 @@ public function testSendMinimalMail()
 
         $this->assertEquals($expectedMessage, $this->connection->getLog());
     }
+
+    public function testDisconnectCallsQuit()
+    {
+        $this->connection->disconnect();
+        $this->assertTrue($this->connection->calledQuit);
+    }
 }

test/TestAsset/SmtpProtocolSpy.php

@@ -21,6 +21,7 @@
  */
 class SmtpProtocolSpy extends Smtp
 {
+    public $calledQuit = false;
     protected $connect = false;
     protected $mail;
     protected $rcptTest = array();
@@ -44,6 +45,7 @@ public function helo($serverName = '127.0.0.1')
 
     public function quit()
     {
+        $this->calledQuit = true;
         parent::quit();
     }