BUG #3750: Invalid frontend message type 112

The following bug has been logged online:

Bug reference: 3750
Logged by: Christian Ullrich
Email address: chris(at)chrullrich(dot)net
PostgreSQL version: 8.3-beta2
Operating system: Windows Server 2003
Description: Invalid frontend message type 112
Details:

I'm running 8.3-beta2 (on WS2003, the client is XP Prof.) to experiment with
SSPI auth against AD. There is a persistent problem when using SSPI:
Authentication appears to work, but the connection fails at the first
query.

psql tells me about an "invalid frontend message type 112". Most of the
time, that error comes as the first line of output from psql (above the
"Welcome to" line), sometimes it is displayed later:

Welcome to psql 8.3beta2, the PostgreSQL interactive terminal.

Type: \copyright for distribution terms
\h for help with SQL commands
\? for help with psql commands
\g or terminate with semicolon to execute query
\q to quit

test=>
test=> select 1;
server closed the connection unexpectedly
This probably means the server terminated abnormally before or while
processing the request.
The connection to the server was lost. Attempting reset: FATAL: invalid
frontend message type 112
Succeeded.

When I use another authentication method, all is well.

I can provide a network trace of the connection on request.