MAINT: added hint

tests/test_file.py

@@ -462,6 +462,8 @@ def test_insert_files_in_dir_error1():
         raise_exception_on_error=False,
         flags={
             "InsertFilesInDir": "/root"})
+    # If this fails, it is likely that the server runs with root permissions
+    # which is discouraged.
     assert_is_not_none(c.messages["Error", 0])
     assert_true(c.messages["Error", 0][0].startswith(
         "Cannot read or enter the desired directory."))