New patch in attachment.
It always uses poll() and maintains and internal fd/Connection map.
I get one failure due to the returned list being sorted differently than when using select() though.


======================================================================
FAIL: test_wait_integer (__main__.TestWait)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "Lib/test/test_multiprocessing.py", line 3277, in test_wait_integer
    self.assertEqual(res, [p.sentinel, b])
AssertionError: Lists differ: [<multiprocessing.connection.C... != [7, <multiprocessing.connectio...

First differing element 0:
<multiprocessing.connection.Connection object at 0x7f8924fccd30>
7

- [<multiprocessing.connection.Connection object at 0x7f8924fccd30>, 7]
?                                                                  ---

+ [7, <multiprocessing.connection.Connection object at 0x7f8924fccd30>]
?  +++




I don't how important this is.
If it's not tests can be adapted accordingly.