Repair name lookup in classes for Py3.6+ after optimising module name lookups.

Cython/Utility/ObjectHandling.c

@@ -1122,12 +1122,14 @@ static PyObject *__Pyx__GetNameInClass(PyObject *nmspace, PyObject *name); /*pro
 //@requires: Exceptions.c::PyErrExceptionMatches
 
 static PyObject *__Pyx_GetGlobalNameAfterAttributeLookup(PyObject *name) {
+    PyObject *result;
     __Pyx_PyThreadState_declare
     __Pyx_PyThreadState_assign
     if (unlikely(!__Pyx_PyErr_ExceptionMatches(PyExc_AttributeError)))
         return NULL;
     __Pyx_PyErr_Clear();
-    return __Pyx__GetModuleGlobalName(name);
+    __Pyx_GetModuleGlobalNameUncached(result, name);
+    return result;
 }
 
 static PyObject *__Pyx__GetNameInClass(PyObject *nmspace, PyObject *name) {
@@ -1165,9 +1167,15 @@ static PyObject *__Pyx__GetNameInClass(PyObject *nmspace, PyObject *name) {
         (likely(__pyx_dict_cached_value) ? __Pyx_NewRef(__pyx_dict_cached_value) : __Pyx_GetBuiltinName(name)) : \
         __Pyx__GetModuleGlobalName(name, &__pyx_dict_version, &__pyx_dict_cached_value); \
 }
+#define __Pyx_GetModuleGlobalNameUncached(var, name)  { \
+    PY_UINT64_T __pyx_dict_version; \
+    PyObject *__pyx_dict_cached_value; \
+    (var) = __Pyx__GetModuleGlobalName(name, &__pyx_dict_version, &__pyx_dict_cached_value); \
+}
 static PyObject *__Pyx__GetModuleGlobalName(PyObject *name, PY_UINT64_T *dict_version, PyObject **dict_cached_value); /*proto*/
 #else
 #define __Pyx_GetModuleGlobalName(var, name)  (var) = __Pyx__GetModuleGlobalName(name)
+#define __Pyx_GetModuleGlobalNameUncached(var, name)  (var) = __Pyx__GetModuleGlobalName(name)
 static CYTHON_INLINE PyObject *__Pyx__GetModuleGlobalName(PyObject *name); /*proto*/
 #endif