fails:Net::FTP#chdir when switching to the parent directory raises a Net::FTPPermError when the response code is 501
fails:Net::FTP#chdir when switching to the parent directory raises a Net::FTPPermError when the response code is 502
fails:Net::FTP#chdir when switching to the parent directory raises a Net::FTPPermError when the response code is 530
fails:Net::FTP#chdir when switching to the parent directory raises a Net::FTPPermError when the response code is 550
