More bug #1077106 stuff, sorry -- modem induced impatiece!

This should go on whatever bugfix branches the other fetches up on.

Misc/NEWS

@@ -21,6 +21,8 @@ Core and builtins
 
 - set and frozenset objects can now be marshalled.  SF #1098985.
 
+- Bug #1077106: Poor argument checking could cause memory corruption
+  in calls to os.read().
 
 Extension Modules
 -----------------

Objects/stringobject.c

@@ -52,6 +52,7 @@ PyObject *
 PyString_FromStringAndSize(const char *str, int size)
 {
 	register PyStringObject *op;
+	assert(size >= 0);
 	if (size == 0 && (op = nullstring) != NULL) {
 #ifdef COUNT_ALLOCS
 		null_strings++;