+
+ except Book.DoesNotExist, e:
+ if file_name not in postponed or postponed[file_name] < files_imported:
+ # push it back into the queue, maybe the missing child will show up
+ if verbose:
+ print self.style.NOTICE('Waiting for missing children')
+ files.append(file_name)
+ postponed[file_name] = files_imported
+ else:
+ # we're in a loop, nothing's being imported - some child is really missing
+ raise e
+