Index: mod/assign/locallib.php
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
--- mod/assign/locallib.php	(date 1538987638000)
+++ mod/assign/locallib.php	(date 1539244621764)
@@ -2729,7 +2729,9 @@
         $params = array('overflowdiv' => true, 'context' => $this->get_context());
         $result .= format_text($finaltext, $format, $params);
 
-        if ($CFG->enableportfolios && has_capability('mod/assign:exportownsubmission', $this->context)) {
+        $actions = array('grading', 'grade', 'viewpluginassignsubmission');
+        if ($CFG->enableportfolios && has_capability('mod/assign:exportownsubmission', $this->context) &&
+            !in_array($this->get_return_action(), $actions)) {
             require_once($CFG->libdir . '/portfoliolib.php');
 
             $button = new portfolio_add_button();
Index: mod/assign/renderable.php
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
--- mod/assign/renderable.php	(date 1538987638000)
+++ mod/assign/renderable.php	(date 1539244823392)
@@ -880,24 +880,6 @@
                                      'timemodified',
                                      false);
 
-        if (!empty($CFG->enableportfolios)) {
-            require_once($CFG->libdir . '/portfoliolib.php');
-            if (count($files) >= 1 && !empty($sid) &&
-                    has_capability('mod/assign:exportownsubmission', $this->context)) {
-                $button = new portfolio_add_button();
-                $callbackparams = array('cmid' => $this->cm->id,
-                                        'sid' => $sid,
-                                        'area' => $filearea,
-                                        'component' => $component);
-                $button->set_callback_options('assign_portfolio_caller',
-                                              $callbackparams,
-                                              'mod_assign');
-                $button->reset_formats();
-                $this->portfolioform = $button->to_html(PORTFOLIO_ADD_TEXT_LINK);
-            }
-
-        }
-
         $this->preprocess($this->dir, $filearea, $component);
     }
 
@@ -910,7 +892,7 @@
      * @return void
      */
     public function preprocess($dir, $filearea, $component) {
-        global $CFG;
+        global $CFG, $USER;
         foreach ($dir['subdirs'] as $subdir) {
             $this->preprocess($subdir, $filearea, $component);
         }
@@ -919,7 +901,7 @@
             if (!empty($CFG->enableportfolios)) {
                 require_once($CFG->libdir . '/portfoliolib.php');
                 $button = new portfolio_add_button();
-                if (has_capability('mod/assign:exportownsubmission', $this->context)) {
+                if (has_capability('mod/assign:exportownsubmission', $this->context) && $USER->id == $file->get_userid() && $filearea != 'feedback_files') {
                     $portfolioparams = array('cmid' => $this->cm->id, 'fileid' => $file->get_id());
                     $button->set_callback_options('assign_portfolio_caller',
                                                   $portfolioparams,