default value if option is set to None

config.py

@@ -330,6 +330,7 @@ class Config(object):
                      child.setowner(self, ['default' for i in range(len(child.getdefault()))])
                 else:
                     child.setowner(self, 'default')
+                self._cfgimpl_values[name] = child.getdefault()
             else:         
                 child.setowner(self, newowner)
         else:

test/test_option_owner.py

@@ -7,7 +7,28 @@ from error import SpecialOwnersError
 
 def make_description():
     gcoption = ChoiceOption('name', 'GC name', ['ref', 'framework'], 'ref')
-    ## dummy 1
+    gcdummy = BoolOption('dummy', 'dummy', default=False, callback="toto")
+    objspaceoption = ChoiceOption('objspace', 'Object space',
+                                ['std', 'thunk'], 'std')
+    booloption = BoolOption('bool', 'Test boolean option', default=True)
+    intoption = IntOption('int', 'Test int option', default=0)
+    floatoption = FloatOption('float', 'Test float option', default=2.3)
+    stroption = StrOption('str', 'Test string option', default="abc")
+    boolop = BoolOption('boolop', 'Test boolean option op', default=True)
+    wantref_option = BoolOption('wantref', 'Test requires', default=False,
+                                    requires=['boolop'])
+    wantframework_option = BoolOption('wantframework', 'Test requires',
+                                      default=False,
+                                      requires=['boolop'])
+    gcgroup = OptionDescription('gc', '', [gcoption, gcdummy, floatoption])
+    descr = OptionDescription('constraints', '', [gcgroup, booloption, objspaceoption,
+                                           wantref_option, stroption,
+                                           wantframework_option,
+                                           intoption, boolop])
+    return descr
+
+def make_description2():
+    gcoption = ChoiceOption('name', 'GC name', ['ref', 'framework'], 'ref')
     gcdummy = BoolOption('dummy', 'dummy', default=False)
     objspaceoption = ChoiceOption('objspace', 'Object space',
                                 ['std', 'thunk'], 'std')
@@ -30,9 +51,9 @@ def make_description():
 
 def test_override_are_default_owner():
     "config.override() implies that the owner is 'default' again"
-    descr = make_description()
+    descr = make_description2()
     config = Config(descr, bool=False)
-    # defaut
+    # default
     assert config.gc._cfgimpl_value_owners['dummy'] == 'default'
     # user
     config.gc.dummy = True

test/test_option_setting.py

@@ -47,7 +47,7 @@ def test_reset():
     assert config.string == "foo"
     assert config._cfgimpl_value_owners['string'] == 'user'
     config.string = None
-    assert config.string == None
+    assert config.string == 'string'
     assert config._cfgimpl_value_owners['string'] == 'default'
 
 def test_idontexist():