Make identifiers str (not str8) objects throughout. This affects the parser, various object implementations, and all places that put identifiers into C string literals. In testing, a number of crashes occurred as code would fail when the recursion limit was reached (such as the Unicode interning dictionary having key/value pairs where key is not value). To solve these, I added an overflowed flag, which allows for 50 more recursions after the limit was reached and the exception was raised, and a recursion_critical flag, which indicates that recursion absolutely must be allowed, i.e. that a certain call must not cause a stack overflow exception. There are still some places where both str and str8 are accepted as identifiers; these should eventually be removed.

--- a/Modules/unicodedata.c	Sat Jun 09 16:13:23 2007 +0000
+++ b/Modules/unicodedata.c	Sun Jun 10 09:51:05 2007 +0000
@@ -515,7 +515,7 @@
             /* Hangul Decomposition adds three characters in
                a single step, so we need atleast that much room. */
             if (space < 3) {
-                Py_ssize_t newsize = PyString_GET_SIZE(result) + 10;
+                Py_ssize_t newsize = PyUnicode_GET_SIZE(result) + 10;
                 space += 10;
                 if (PyUnicode_Resize(&result, newsize) == -1)
                     return NULL;