Fixed a nested scopes bug reported by jellej@pacbell.net. Thanks!

Evan's description:

If you defined two nested functions in a row that refer to the same
non-global variable, the second one will be generated as though the
variable were global.

lib/python/RestrictedPython/compiler/symbols.py

@@ -162,12 +162,12 @@ class Scope:
                     child_globals.append(name)
                 elif isinstance(self, FunctionScope) and sc == SC_LOCAL:
                     self.cells[name] = 1
-                else:
+                elif sc != SC_CELL:
                     child_globals.append(name)
             else:
                 if sc == SC_LOCAL:
                     self.cells[name] = 1
-                else:
+                elif sc != SC_CELL:
                     child_globals.append(name)
         return child_globals
 

lib/python/RestrictedPython/tests/restricted_module.py

+from __future__ import nested_scopes
 
 def print0():
     print 'Hello, world!',
@@ -136,4 +137,12 @@ def rot13(ss):
         res = res + mapping.get(c, c)
     return res
 
+def nested_scopes_1():
+    # Fails if 'a' is consumed by the first function.
+    a = 1
+    def f1():
+        return a
+    def f2():
+        return a
+    return f1() + f2()
 

lib/python/RestrictedPython/tests/testRestrictions.py

@@ -57,7 +57,7 @@ def create_rmodule():
     compile(source, fn, 'exec')
     # Now compile it for real
     code = compile_restricted(source, fn, 'exec')
-    rmodule = {'__builtins__':None}
+    rmodule = {'__builtins__':{'__import__':__import__, 'None':None}}
     builtins = getattr(__builtins__, '__dict__', __builtins__)
     for name in ('map', 'reduce', 'int', 'pow', 'range', 'filter',
                  'len', 'chr', 'ord',
@@ -250,6 +250,10 @@ class RestrictionTests(unittest.TestCase):
         res = self.execFunc('rot13', 'Zope is k00l')
         assert (res == 'Mbcr vf x00y'), res
 
+    def checkNestedScopes1(self):
+        res = self.execFunc('nested_scopes_1')
+        assert (res == 2), res
+
     def checkUnrestrictedEval(self):
         expr = RestrictionCapableEval("{'a':[m.pop()]}['a'] + [m[0]]")
         v = [12, 34]