MDL-69106 assignfeedback_editpdf: Keep files in conversion queue

In some circumstances, a submission waiting to be converted needs to persist
in the conversion queue so that it can be polled on subsequent cron runs.

mod/assign/feedback/editpdf/classes/task/convert_submissions.php

@@ -98,6 +98,7 @@ public function execute() {
             }
 
             mtrace('Convert ' . count($users) . ' submission attempt(s) for assignment ' . $assignmentid);
+            $conversionrequirespolling = false;
 
             foreach ($users as $userid) {
                 try {
@@ -107,6 +108,7 @@ public function execute() {
                         case combined_document::STATUS_READY_PARTIAL:
                         case combined_document::STATUS_PENDING_INPUT:
                             // The document has not been converted yet or is somehow still ready.
+                            $conversionrequirespolling = true;
                             continue 2;
                     }
                     document_services::get_page_images_for_attempt(
@@ -127,7 +129,9 @@ public function execute() {
             }
 
             // Remove from queue.
-            $DB->delete_records('assignfeedback_editpdf_queue', array('id' => $record->id));
+            if (!$conversionrequirespolling) {
+                $DB->delete_records('assignfeedback_editpdf_queue', array('id' => $record->id));
+            }
 
         }
     }