piping doesn't work with dropbear server

[untoreh]

I have tested piping a bash script, trying to pipe to a dropbear ssh server returns

Process exited with status 129 from signal HUP

While quickly testing with sshd it works as intended. Testing with with just the ssh client (standard openssh client)

echo "echo hello" | ssh user@dropbearhost bash

works so I don't know what golang ssh or sup does differently

[VojtechVitek]

Please, provide a full reproducer

[untoreh]

# Supfile
version: 0.4

networks:
  test:
    hosts:
      - root@localhost:2222


commands:
  bash:
    desc: Interactive Bash on all hosts
    stdin: true
    run: >
      bash -l
targets:

dropbear

docker run --rm -it --net=host alpine sh -c "apk add --no-cache dropbear; mkdir -p /etc/dropbear; mkdir ~/.ssh; chmod 700 ~/.ssh; echo $SSH_KEY > ~/.ssh/authorized_keys; dropbear -p 2222 -REF"

sup

echo "hello" | sup test bash