I tried a few ways to get the timeout to trigger (suspending wget in the
middle of an attachment or page download etc.) with no luck.

Per:

    https://docs.python.org/2/library/socket.html

=====
 exception socket.timeout
    This exception is raised when a timeout occurs on a socket which has
had timeouts enabled via a prior call to settimeout(). The accompanying
value is a string whose value is currently always “timed out”.
[...]
Some notes on socket blocking and timeouts: A socket object can be in
one of three modes: blocking, non-blocking, or timeout. Sockets are
always created in blocking mode. In blocking mode, operations block
until complete or the system returns an error (such as connection timed
out). In non-blocking mode, 
====

I can't find a call to settimeout anywhere in the roundup code. The fact
that blocking mode can return a timeout seems well wrong.

However checking out the code in hg as of: 2012-08-27 also shows no
settimeout, so .... However settimeout was new in python 2.3. I don't
know if something changed in python that would make this patch obsolete.