[BUG] Lftp commands leave defunct processes

[sernad]

Hi happy new year :D, we recently noticed that after running commands such as:

• mkdir -p -f "/destination_route"

• mirror --verbose=3 --log="/tmp/lftp.log" --no-empty-dirs --no-perms -P 10 -R "/tmp/lftpFile/" "/destination_route/";

Some ssh and sh processes linger after the execution (See image below). The file transfer and directories creation works OK, the problem are the defunct processes

We have tested:

1. Running the lftp commands in a container to only see the new processes and isolate other variables
2. Running the commands with the -c parameter
3. Passing parameters in a file
4. Upgrading lftp to the latest version (4.9.2 at the time of this post)

[alexkorsun]

We noticed the same issue on our end. Over time the number of processes goes to thousands, so they don't quit.
As an example, there is the command:

lftp -c 'set sftp:auto-confirm yes; set sftp:connect-program "ssh -a -x -i local-private-key" ; open -u "XXX","YYY" sftp://sftp-1:22; cls -1 --date --size -h --perms --block-size 1 ; exit'