select.select fails on file-like objects created by socket.makefile when data exists in the file buffer but not in the underlying socket.

Here is code to reproduce the bug.  Run it, then point a web browser at port 8080 and observer that select times out indicating that no input is available even though input is still in fact available.

=======

from SocketServer import *
from socket import *
from select import select

class myHandler(StreamRequestHandler):
  def handle(self):
    while 1:
      sl = select([self.rfile],[],[],1)[0]
      print sl
      l = self.rfile.readline()
      if len(l)<3: break
      print l,
      pass
    print>>self.wfile, 'HTTP/1.0 200 OK'
    print>>self.wfile, 'Content-type: text/plain'
    print>>self.wfile
    print>>self.wfile, 'foo'

server = TCPServer(('',8080), myHandler)
server.serve_forever()

The handler should not do its own select() call. (And even then, select should use the underlying socket, not the wrapping pseudo-file object).
Just removing the select() call works fine.

>Just removing the select() call works fine.

For this simple example yes, not for more complicated cases.  My particular application is a transparent HTTP proxy which needs to be able to serve multiple connections at once and handle keep-alive connections.  (The proxy connects to local server processes through unix sockets, which is why I can't use a regular HTTP proxy.  Send me email if you want more details about why I'm doing this.)  Without writing a full-blown HTTP-aware proxy, select (or something like it) is necessary.

Upon further study, though, I have come to the conclusion that this is not actually a bug (since select is doing what it is advertised to do), just very counter-intituitive behavior.  If select is going to accept file objects as arguments it ought to do the Right Thing with them IMO.

Cannot verify for trunk.

This older post 
http://bytes.com/groups/python/786579-python-2-2-1-select
describes a similar problem where select() is used on a buffered file
object (a pipe to another process)

IMO it should be documented that select() does not work so well for
objects which have a fileno(), but do data buffering: select() only sees
the file descriptor and cannot know whether there is data in the buffer.