Issue #2405337 by benjy: EntityFile destination doesn't handle temporary files...

Issue #2405337 by benjy: EntityFile destination doesn't handle temporary files when the source and destination are the same

core/modules/migrate/src/Plugin/migrate/destination/EntityFile.php

@@ -50,6 +50,11 @@ public function import(Row $row, array $old_destination_id_values = array()) {
     // already absolute.
     $source = $this->isTempFile($destination) ? $file : $this->configuration['source_base_path'] . $file;
 
+    // If the start and end file is exactly the same, there is nothing to do.
+    if (drupal_realpath($source) === drupal_realpath($destination)) {
+      return parent::import($row, $old_destination_id_values);
+    }
+
     $replace = FILE_EXISTS_REPLACE;
     if (!empty($this->configuration['rename'])) {
       $entity_id = $row->getDestinationProperty($this->getKey('id'));

core/modules/migrate_drupal/src/Tests/d6/MigrateFileTest.php

@@ -29,6 +29,9 @@ class MigrateFileTest extends MigrateDrupalTestBase {
    * {@inheritdoc}
    */
   protected function setUp() {
+    // Set the temp file of the site to the same as the D6 site, this allows us
+    // to test files which start and finish in the same place.
+    $this->tempFilesDirectory = '/tmp';
     parent::setUp();
     $dumps = array(
       $this->getDumpDirectory() . '/Files.php',