Fix the builtin module initialization code to store the init function for future reinitialization.

Misc/NEWS

@@ -10,6 +10,9 @@ What's New in Python 3.3 Alpha 1?
 Core and Builtins
 -----------------
 
+- Fix the builtin module initialization code to store the init function for
+  future reinitialization.
+
 - Issue #13629: Renumber the tokens in token.h so that they match the indexes
   into _PyParser_TokenNames.
 

Python/import.c

@@ -2542,6 +2542,7 @@ init_builtin(PyObject *name)
 
     for (p = PyImport_Inittab; p->name != NULL; p++) {
         PyObject *mod;
+        PyModuleDef *def;
         if (PyUnicode_CompareWithASCIIString(name, p->name) == 0) {
             if (p->initfunc == NULL) {
                 PyErr_Format(PyExc_ImportError,
@@ -2554,6 +2555,9 @@ init_builtin(PyObject *name)
             mod = (*p->initfunc)();
             if (mod == 0)
                 return -1;
+            /* Remember pointer to module init function. */
+            def = PyModule_GetDef(mod);
+            def->m_base.m_init = p->initfunc;
             if (_PyImport_FixupExtensionObject(mod, name, name) < 0)
                 return -1;
             /* FixupExtension has put the module into sys.modules,