Note: only the relevant parts of r79474 are merged.

Merged revisions 78793,78798-78799,78977,79095,79196,79474 via svnmerge from
svn+ssh://pythondev@svn.python.org/python/branches/py3k

................
  r78793 | florent.xicluna | 2010-03-08 13:25:35 +0100 (lun, 08 mar 2010) | 2 lines

  Fix macpath to deal with bytes
................
  r78798 | florent.xicluna | 2010-03-08 14:32:17 +0100 (lun, 08 mar 2010) | 18 lines

  Merged revisions 78777,78787,78790 via svnmerge from
  svn+ssh://pythondev@svn.python.org/python/trunk

  ........
    r78777 | florent.xicluna | 2010-03-08 00:49:03 +0100 (lun, 08 mar 2010) | 4 lines

    Backport the Popen.poll() protection from subprocess to multiprocessing. See #1731717.
    It should fix transient failures on test_multiprocessing.
  ........
    r78787 | florent.xicluna | 2010-03-08 08:21:16 +0100 (lun, 08 mar 2010) | 2 lines

    Don't fail on a debug() statement, if the worker PID is (still) None.
  ........
    r78790 | florent.xicluna | 2010-03-08 12:01:39 +0100 (lun, 08 mar 2010) | 2 lines

    On finalize, don't try to join not started process.
  ........
................
  r78799 | florent.xicluna | 2010-03-08 15:44:41 +0100 (lun, 08 mar 2010) | 2 lines

  Fix ntpath abspath to deal with bytes.
................
  r78977 | florent.xicluna | 2010-03-15 14:14:39 +0100 (lun, 15 mar 2010) | 2 lines

  Fix \xhh specs, #1889.  (an oversight of r60193, r60210).
................
  r79095 | florent.xicluna | 2010-03-19 15:40:31 +0100 (ven, 19 mar 2010) | 2 lines

  Rename test.test_support to test.support for 3.x.
................
  r79196 | florent.xicluna | 2010-03-21 13:29:50 +0100 (dim, 21 mar 2010) | 9 lines

  Merged revisions 79195 via svnmerge from
  svn+ssh://pythondev@svn.python.org/python/trunk

  ........
    r79195 | florent.xicluna | 2010-03-21 13:27:20 +0100 (dim, 21 mar 2010) | 2 lines

    Issue #8179: Fix macpath.realpath() on a non-existing path.
  ........
................
  r79474 | florent.xicluna | 2010-03-28 01:25:02 +0100 (dim, 28 mar 2010) | 33 lines

  Merged revisions 79297,79310,79382,79425-79427,79450 via svnmerge from
  svn+ssh://pythondev@svn.python.org/python/trunk

  ........
    r79297 | florent.xicluna | 2010-03-22 18:18:18 +0100 (lun, 22 mar 2010) | 2 lines

    #7668: Fix test_httpservers failure when sys.executable contains non-ASCII bytes.
  ........
    r79310 | florent.xicluna | 2010-03-22 23:52:11 +0100 (lun, 22 mar 2010) | 2 lines

    Issue #8205: Remove the "Modules" directory from sys.path when Python is running from the build directory (POSIX only).
  ........
    r79382 | florent.xicluna | 2010-03-24 20:33:25 +0100 (mer, 24 mar 2010) | 2 lines

    Skip tests which depend on multiprocessing.sharedctypes, if _ctypes is not available.
  ........
    r79425 | florent.xicluna | 2010-03-25 21:32:07 +0100 (jeu, 25 mar 2010) | 2 lines

    Syntax cleanup `== None` -> `is None`
  ........
    r79426 | florent.xicluna | 2010-03-25 21:33:49 +0100 (jeu, 25 mar 2010) | 2 lines

    #8207: Fix test_pep277 on OS X
  ........
    r79427 | florent.xicluna | 2010-03-25 21:39:10 +0100 (jeu, 25 mar 2010) | 2 lines

    Fix test_unittest and test_warnings when running "python -Werror -m test.regrtest"
  ........
    r79450 | florent.xicluna | 2010-03-26 20:32:44 +0100 (ven, 26 mar 2010) | 2 lines

    Ensure that the failed or unexpected tests are sorted before printing.
  ........
................
diff --git a/Lib/multiprocessing/forking.py b/Lib/multiprocessing/forking.py
index 3c0f568..5d66fa3 100644
--- a/Lib/multiprocessing/forking.py
+++ b/Lib/multiprocessing/forking.py
@@ -104,7 +104,12 @@
 
         def poll(self, flag=os.WNOHANG):
             if self.returncode is None:
-                pid, sts = os.waitpid(self.pid, flag)
+                try:
+                    pid, sts = os.waitpid(self.pid, flag)
+                except os.error:
+                    # Child process not yet created. See #1731717
+                    # e.errno == errno.ECHILD == 10
+                    return None
                 if pid == self.pid:
                     if os.WIFSIGNALED(sts):
                         self.returncode = -os.WTERMSIG(sts)