crash bug on closed connection

I have been looking into this crash for a while now, and I finally have a
good repro.

After digging through it with wireshark I observed this
client tries to send a query
retransmit query
retransmit query
...
client sends TCP [RST],[ACK]
Now it has crashed, so we restart it again and begin another connection
successfully.

It seems that the connection has dropped, but the client was never
informed, and it doesn't handle this gracefully.

I reproed it like this:

On my mac running postgres server:
Setup port forwarding to emulate a proxy or firewall problem
ssh -L [public ip]:5433:localhost:5432 -N localhost

On my windows machine:
Connect to port 5433 on my mac
Run a query

On my mac:
Kill the ssh proxy
sighub postgres
open the ssh proxy again

On my windows machine:
Run another query (was never informed that the connection dropped)
Crash in