add brief note on compiler support

pep-0227.txt

@@ -329,6 +329,12 @@ Implementation
     definition time.  This is the default argument hack, but not
     actual name resolution based on statically nested scopes.
 
+    It is not clear whether the current 1-pass Python compiler can
+    determine which references are to globals and which are references
+    to enclosing scopes.  It may be possible to make minimal changes
+    that defers the optimize() call until a second pass, after scopes
+    have been determined.
+
 
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