This is very similar to the following issue, but the source file is different and it still occurs
in 1.3.2:
http://sourceforge.net/tracker/index.php?func=detail&aid=1600727&group_id=31577&atid=402788

In my case the server dumps the following to stderr:
Exception happened during processing of request from ('172.28.75.61', 7106)
Traceback (most recent call last):
  File "/Projects/software/IA32-LIN/python2.3.4/lib/python2.3/SocketServer.py", line 440, in process_request
    self.finish_request(request, client_address)
  File "/Projects/software/IA32-LIN/python2.3.4/lib/python2.3/SocketServer.py", line 254, in finish_request
    self.RequestHandlerClass(request, client_address, self)
  File "/Projects/software/IA32-LIN/python2.3.4/lib/python2.3/SocketServer.py", line 521, in __init__
    self.handle()
  File "/Projects/software/IA32-LIN/python2.3.4/lib/python2.3/BaseHTTPServer.py", line 324, in handle
    self.handle_one_request()
  File "/Projects/software/IA32-LIN/python2.3.4/lib/python2.3/BaseHTTPServer.py", line 318, in handle_one_request
    method()
  File "/Projects/psp/roundup/roundup-1.3.2/lib/python2.3/site-packages/roundup/scripts/roundup_server.py", line 118, in run_cgi
    self.send_response(400)
  File "/Projects/software/IA32-LIN/python2.3.4/lib/python2.3/BaseHTTPServer.py", line 374, in send_response
    self.wfile.write("%s %d %s\r\n" %
  File "/Projects/software/IA32-LIN/python2.3.4/lib/python2.3/socket.py", line 254, in write
    self.flush()
  File "/Projects/software/IA32-LIN/python2.3.4/lib/python2.3/socket.py", line 241, in flush
    self._sock.sendall(buffer)
timeout: timed out

The email that I get in that case says:

Traceback (most recent call last):

  File "/Projects/psp/roundup/roundup-1.3.2/lib/python2.3/site-packages/roundup/cgi/client.py", line 290, in inner_main
    self.write_html(self.renderContext())

  File "/Projects/psp/roundup/roundup-1.3.2/lib/python2.3/site-packages/roundup/cgi/client.py", line 879, in write_html
    self.header()

  File "/Projects/psp/roundup/roundup-1.3.2/lib/python2.3/site-packages/roundup/cgi/client.py", line 920, in header
    self._socket_op(self.request.start_response, headers, response)

  File "/Projects/psp/roundup/roundup-1.3.2/lib/python2.3/site-packages/roundup/cgi/client.py", line 865, in _socket_op
    if err.errno not in self.IGNORE_NET_ERRORS:

AttributeError: error instance has no attribute 'errno'

Forgot to mention that I run it with Python 2.3.4 on Linux (some SUSE derived distro).

I believe this is fixed in current CVS.