I can confirm that Alex's commit to x2goserver (rather than x2goclient) fixes this bug.
bf318affee905cf7cdeaa5a248dfd07bc46a8a96 Clean user SSHD process if connection between server and client lost. This should fix error "Global request tcpip-forward failed". http://code.x2go.org/gitweb?p=x2goserver.git;a=commit;h=bf318affee905cf7cdea...
Mike#1 Should I retitle and reassign this bug (#547) to x2goserver? And should we cherry-pick it for x2goserver release/4.0.0.x & release/4.0.1.x? We should probably release updated versions of 4.0.0.x (baikal) and 4.0.1.x at least a month before we release x2goclient 4.0.3.0. Otherwise, people will run into this bug if they update their clients to 4.0.3.0 but do not update their servers.
-Mike#2