Fix EBADF when closing fds in parent for ForkedJob

                try:

                    os.close(fd)

                except OSError as exc:

                    if exc.errno == errno.EBADF:

                        # FIXME this is weird but it seems to happen sometimes

                        logger.debug('Error while closing fd in parent, EBADF')

                        continue

                    logger.error('Error while closing fds in parent: %s',

                                 os.strerror(exc.errno))

                    raise