Good grief. When I originally wrote the local proxy code two years

Good grief. When I originally wrote the local proxy code two years
ago, I apparently caused all data received from local proxies to be
unconditionally tagged as TCP Urgent. Most network backends ignore
this, but it's critical to the Telnet backend, which will ignore all
Urgent-marked data in the assumption that there's a SYNCH on its way
that it should wait for. Nobody has noticed in two years, presumably
meaning that nobody has ever tried to do Telnet over a local proxy
in that time.

git-svn-id: svn://svn.tartarus.org/sgt/putty@8158 cda61777-01e9-0310-a592-d414129be87e