Merge branch '6.4' into 7.1

* 6.4:
  fix merge
  pass CSV escape characters explicitly
  move setting deprecation session options into a legacy group test

Dumper/CsvFileDumper.php

@@ -28,7 +28,7 @@ public function formatCatalogue(MessageCatalogue $messages, string $domain, arra
         $handle = fopen('php://memory', 'r+');
 
         foreach ($messages->all($domain) as $source => $target) {
-            fputcsv($handle, [$source, $target], $this->delimiter, $this->enclosure);
+            fputcsv($handle, [$source, $target], $this->delimiter, $this->enclosure, '\\');
         }
 
         rewind($handle);