Fix TTSSH (Tera Type/Term) client crash:

Unexpected SSH2 message(80) on current stage(6)

This patch was submitted upstream. The client has fixed it in their SVN [1][2]
but not yet released a fixed build.

[1] http://en.sourceforge.jp/ticket/browse.php?group_id=1412&tid=35010
[2] http://en.sourceforge.jp/projects/ttssh2/scm/svn/commits/5829