Putty does not exit when remote command terminates

[Antoine Martin]

In ssh-mode, we launch a remote X command and putty is still running when the command terminates.
This causes the session to remain "active" on the client despite the fact that it is really finished...

This happens with all the clients we can use: TortoisePlink?.exe, Plink.exe as well as openssh (via cygwin).
Looks like the clients refuse to shutdown whilst there is still a tunnel (the X display connection) so we may have to use a trick on the server and run the command via a wrapper which will take care of killing the ssh process when the command terminates.