Issue #14753: Make multiprocessing treat negative timeouts as it did in 3.2

In Python 3.2 and earlier, Process.join() and Connection.poll()
treated negative timeouts as zero timeouts.  Earlier versions from
the 3.3 line of development treat them as infinite timeouts.

The patch reverts to the old behaviour.

Lib/multiprocessing/connection.py

@@ -23,8 +23,7 @@ import itertools
 
 import _multiprocessing
 from multiprocessing import current_process, AuthenticationError, BufferTooShort
-from multiprocessing.util import (
-    get_temp_dir, Finalize, sub_debug, debug, _eintr_retry)
+from multiprocessing.util import get_temp_dir, Finalize, sub_debug, debug
 from multiprocessing.forking import ForkingPickler
 try:
     import _winapi
@@ -323,8 +322,6 @@ if _winapi:
             if (self._got_empty_message or
                         _winapi.PeekNamedPipe(self._handle)[0] != 0):
                 return True
-            if timeout < 0:
-                timeout = None
             return bool(wait([self], timeout))
 
         def _get_more_data(self, ov, maxsize):
@@ -402,8 +399,6 @@ class Connection(_ConnectionBase):
         return self._recv(size)
 
     def _poll(self, timeout):
-        if timeout < 0.0:
-            timeout = None
         r = wait([self._handle], timeout)
         return bool(r)