select.poll returning strange file descriptors.

[Simon Wittber]

I'm using the poll object from select.poll to check for events on
sockets.

It seems to work, however when I call .poll() on the poll objects, I
sometimes get a fileno 1 returned, which is strange, because none of
the sockets I registered with the poll object have a fileno of 1. In
fact, the sockets all start from fileno 3 and go up from there.

Does anybody know why this is happening?