http://expat.cvs.sourceforge.net/viewvc/expat/expat/lib/xmltok_impl.c?view=log (1.13 -> 1.15)
http://svn.python.org/view?view=rev&revision=74429

--- lib/xmltok_impl.c
+++ lib/xmltok_impl.c
@@ -1744,7 +1744,7 @@
                        const char *end,
                        POSITION *pos)
 {
-  while (ptr != end) {
+  while (ptr < end) {
     switch (BYTE_TYPE(enc, ptr)) {
 #define LEAD_CASE(n) \
     case BT_LEAD ## n: \