work-around for ticket #691: look up unknown global names in builtins at runtime

Cython/Compiler/ExprNodes.py

@@ -7691,11 +7691,18 @@ impl = """
 static PyObject *__Pyx_GetName(PyObject *dict, PyObject *name) {
     PyObject *result;
     result = PyObject_GetAttr(dict, name);
-    if (!result)
-        PyErr_SetObject(PyExc_NameError, name);
+    if (!result) {
+        if (dict != %(BUILTINS)s) {
+            PyErr_Clear();
+            result = PyObject_GetAttr(%(BUILTINS)s, name);
+        }
+        if (!result) {
+            PyErr_SetObject(PyExc_NameError, name);
+        }
+    }
     return result;
 }
-""")
+""" % {'BUILTINS' : Naming.builtins_cname})
 
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