Merged revisions 70908,70939,71009,71022,71036 via svnmerge from
svn+ssh://pythondev@svn.python.org/python/trunk

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  r70908 | jesse.noller | 2009-03-31 17:20:35 -0500 (Tue, 31 Mar 2009) | 1 line

  Issue 5619: Pass MS CRT debug flags into subprocesses
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  r70939 | jesse.noller | 2009-03-31 22:45:50 -0500 (Tue, 31 Mar 2009) | 1 line

  Fix multiprocessing.event to match the new threading.Event API
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  r71009 | jesse.noller | 2009-04-01 19:03:28 -0500 (Wed, 01 Apr 2009) | 1 line

  issue5545: Switch to Autoconf for multiprocessing; special thanks to Martin Lowis for help
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  r71022 | jesse.noller | 2009-04-01 21:32:55 -0500 (Wed, 01 Apr 2009) | 1 line

  Issue 3110: Additional protection for SEM_VALUE_MAX on platforms, thanks to Martin Loewis
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  r71036 | jesse.noller | 2009-04-01 23:22:09 -0500 (Wed, 01 Apr 2009) | 1 line

  Issue 3551: Raise ValueError if the size causes ERROR_NO_SYSTEM_RESOURCES
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diff --git a/Modules/_multiprocessing/connection.h b/Modules/_multiprocessing/connection.h
index 581beac..2ee5368 100644
--- a/Modules/_multiprocessing/connection.h
+++ b/Modules/_multiprocessing/connection.h
@@ -139,8 +139,12 @@
 	res = conn_send_string(self, buffer + offset, size);
 
 	PyBuffer_Release(&pbuffer);
-	if (res < 0)
-		return mp_SetError(PyExc_IOError, res);
+	if (res < 0) {
+		if (PyErr_Occurred())
+			return NULL;
+		else
+			return mp_SetError(PyExc_IOError, res);
+	}
 
 	Py_RETURN_NONE;
 }