My x2go server is my desktop at work and there is a .bashrc that launches keychain and loads my ~/.ssh/id_dsa into the session environment.

the terminal gets the following output before the prompt:

 * keychain 2.7.1 ~ http://www.funtoo.org
 * Found existing ssh-agent: 1829
 * Known ssh key: /home/rhall/.ssh/id_dsa

Then you get a bash prompt.

This output becomes the text of the error message when I try to connect to this same box via x2go-client.

The relevant lines in .bashrc are:

/usr/bin/keychain ~/.ssh/id_dsa
source ~/.keychain/rhall-sh