BUG #4527: Prepare of large multirow insert fails without error

The following bug has been logged online:

Bug reference: 4527
Logged by: Vincent Kessler
Email address: vincent(dot)kessler(at)quantec-networks(dot)de
PostgreSQL version: 8.3.4
Operating system: Debian Linux 2.6.18-6-686-bigmem
Description: Prepare of large multirow insert fails without error
Details:

Hi,

i am trying to do large multirow inserts using PQsendPrepare. I have not
found a limit in the number of parameters or the size of the querystring, so
i assume memory is the limit.
When executing the PQsendPrepare function using a querystring of about 100kb
in size and about 10000 parameters the function returns after timeout. A
tcpdump shows a "parse" message with a length of 100kb but the transfer
stops after roughly 30kb.

The server log shows:
LOG: incomplete message from client
LOG: unexpected EOF on client connection

A pcap file for analysis using tcpdump or wireshark is available here:
http://www.quantec-networks.de/downloads/dump.pcap

I have no quick way to upgrade to 8.3.5 but according to the changelog it
should not be relevant in this case.

What can i do to narrow down the problem?
Any help is greatly apreciated.

Regards,

Vincent