Weird error messages from Windows upon client death

On windows, if the client gets terminated while sending data to the server,
in a COPY for example, it results in some rather head-scratcher messages in
the server log, for example:

LOG: could not receive data from client: No connection could be made
because the target machine actively refused it.

Since the server was reading from the client and never tries to initiate a
connection, the %m part of the message is a bit baffling. The errno at
this point is 10061.

Googling for "No connection could be made because the target machine
actively refused it", I can't find any mentions for it that occur in a
context in which a connection is not being attempted, except for from
PostgreSQL. So I think we must be doing something wrong but I can't figure
out what that would be (no strace, not gdb). Any tips on how to figure out
why this is happening?

I run the below, and then terminated it with a ctrl-C. This is with 9.4dev
compiled with MinGW, but I've seen (unconfirmed by me) reports of the same
%m from the Windows binary distribution for a production version.

perl -le 'print rand() foreach 1..10000000' | psql -c 'copy foo from stdin'

Cheers,

Jeff