Add some asserts

Author: markshannon

Include/refcount.h

@@ -390,6 +390,7 @@ static inline void Py_DECREF_MORTAL(const char *filename, int lineno, PyObject *
         _Py_NegativeRefcount(filename, lineno, op);
     }
     _Py_DECREF_STAT_INC();
+    assert(!_Py_IsStaticImmortal(op));
     if (!_Py_IsImmortal(op)) {
         _Py_DECREF_DecRefTotal();
     }
@@ -407,6 +408,7 @@ static inline void _Py_DECREF_MORTAL_SPECIALIZED(const char *filename, int linen
         _Py_NegativeRefcount(filename, lineno, op);
     }
     _Py_DECREF_STAT_INC();
+    assert(!_Py_IsStaticImmortal(op));
     if (!_Py_IsImmortal(op)) {
         _Py_DECREF_DecRefTotal();
     }
@@ -442,6 +444,7 @@ static inline void Py_DECREF(const char *filename, int lineno, PyObject *op)
 #else
 static inline void Py_DECREF_MORTAL(PyObject *op)
 {
+    assert(!_Py_IsStaticImmortal(op));
     _Py_DECREF_STAT_INC();
     if (--op->ob_refcnt == 0) {
         _Py_Dealloc(op);
@@ -451,6 +454,7 @@ static inline void Py_DECREF_MORTAL(PyObject *op)
 
 static inline void Py_DECREF_MORTAL_SPECIALIZED(PyObject *op, destructor destruct)
 {
+    assert(!_Py_IsStaticImmortal(op));
     _Py_DECREF_STAT_INC();
     if (--op->ob_refcnt == 0) {
         destruct(op);