wagon-ssh download hangs

To reproduce this issue

1. checkout https://github.com/mojohaus/wagon-maven-plugin.git
2. Locally build maven 3.6.1-SNAPSHOT with wagon 3.3.0 and run it with
3. cd src/test/project/ssh-it; mvn -Dit-plugin.version=2.0.0

Assume your local account can ssh to same host with ssh key

other notes:

• No problem with maven 3.6.0
• I also have internal ssh library wrapper of wagon-ssh to perform sshexe/upload/download activities. Seeing the same issue with wagon 3.3.0
• The root cause likely is from WAGON-537 with changes at AbstractWagon which may have side effect on internal JSCH 32K buffer

Reverting WAGON-537 fixes this issue