MLST responses sometimes have blank lines which confuses GetEntry

[ncw]

Describe the bug

Some FTP servers (in particular these two android servers, but there may be others

• FTP Serveur WiFi
• Serveur FTP

Return a blank line in their MLST responses.

To Reproduce

   MLST Download
    250-
    Size=53248;Modify=20230327134339.000;Type=dir; Download

    250 Requested file action okay, completed.

Expected behavior

This causes GetEntry to return this error

unsupported LIST line

FTP server

• FTP Serveur WiFi
• Serveur FTP