SF patch #1055159 via Titus Brown: Document redirect limitation.

Bug fix candidate.

Doc/lib/libcgihttp.tex

@@ -18,6 +18,11 @@ run CGI scripts.
 on Mac OS it will only be able to run Python scripts within the same
 process as itself.}
 
+\note{CGI scripts run by the \class{CGIHTTPRequestHandler} class cannot execute
+redirects (HTTP code 302), because code 200 (script output follows)
+is sent prior to execution of the CGI script.  This pre-empts the status
+code.}
+
 The \module{CGIHTTPServer} module defines the following class:
 
 \begin{classdesc}{CGIHTTPRequestHandler}{request, client_address, server}

Lib/CGIHTTPServer.py

@@ -14,6 +14,8 @@ requests are executed sychronously.
 SECURITY WARNING: DON'T USE THIS CODE UNLESS YOU ARE INSIDE A FIREWALL
 -- it may execute arbitrary Python code or external programs.
 
+Note that status code 200 is sent prior to execution of a CGI script, so
+scripts cannot send other status codes such as 302 (redirect).
 """