Issue #2174997 by alexpott: Random fail in ImageFieldDisplayTest.

core/modules/simpletest/lib/Drupal/simpletest/TestBase.php

@@ -1342,7 +1342,9 @@ public function randomStringValidate($string) {
     }
 
     // Starting with a space means that length might not be what is expected.
-    if (preg_match('/^\s/', $string)) {
+    // Starting with an @ sign causes CURL to fail if used in conjunction with a
+    // file upload, see https://drupal.org/node/2174997.
+    if (preg_match('/^(\s|@)/', $string)) {
       return FALSE;
     }
 

core/modules/simpletest/tests/Drupal/simpletest/Tests/TestBaseTest.php

@@ -48,6 +48,8 @@ public function randomStringValidateProvider () {
       array('curry   paste', FALSE),
       array('curry paste', TRUE),
       array('thai green curry paste', TRUE),
+      array('@startswithat', FALSE),
+      array('contains@at', TRUE),
     );
   }