Ensure unique form entries are made with each ticket

Fixes a case where multiple tickets are created in one request (such as a
cron job triggering multiple email fetches). The TicketForm::getInstance()
called in Ticket::create() used a singleton pattern to retrieve a cached
instance of the TicketForm. In the case of ticket creation, each ticket
needs a new TicketForm entry instance.

include/class.dynamic_forms.php

@@ -179,12 +179,15 @@ class TicketForm extends DynamicForm {
     }
 
     static function getInstance() {
-        if (!isset(static::$instance)) {
-            $o = static::objects();
-            static::$instance = $o[0]->instanciate();
-        }
+        if (!isset(static::$instance))
+            static::$instance = static::getNewInstance();
         return static::$instance;
     }
+
+    static function getNewInstance() {
+        $o = static::objects();
+        return $o[0]->instanciate();
+    }
 }
 // Add fields from the standard ticket form to the ticket filterable fields
 Filter::addSupportedMatches('Custom Fields', function() {
@@ -698,7 +701,7 @@ class DynamicList extends VerySimpleModel {
         return $selections;
     }
 }
-FormField::addFieldTypes('Custom Lists', array(DynamicList, 'getSelections'));
+FormField::addFieldTypes('Custom Lists', array('DynamicList', 'getSelections'));
 
 /**
  * Represents a single item in a dynamic list

include/class.ticket.php

@@ -1928,7 +1928,7 @@ class Ticket {
         }
 
         // Create and verify the dynamic form entry for the new ticket
-        $form = TicketForm::getInstance();
+        $form = TicketForm::getNewInstance();
         // If submitting via email, ensure we have a subject and such
         foreach ($form->getFields() as $field) {
             $fname = $field->get('name');