fix overriding Parameter with value

a property declared in a base class may be overriden
with a parameter in a subclass. this is already allowed.
if then, in the subsubclass it is overridden by a bare value,
it fails.

Patchset 1: add a test for this
Patchset 4: add the fix

Change-Id: Ia5a26076a9ee98439932643a03878342d56f8396
Reviewed-on: https://forge.frm2.tum.de/review/c/secop/frappy/+/35932
Reviewed-by: Markus Zolliker <markus.zolliker@psi.ch>
Tested-by: Jenkins Automated Tests <pedersen+jenkins@frm2.tum.de>

test/test_modules.py

@@ -31,6 +31,7 @@ from frappy.modules import Communicator, Drivable, Readable, Module, Writable
 from frappy.params import Command, Parameter, Limit
 from frappy.rwhandler import ReadHandler, WriteHandler, nopoll
 from frappy.lib import generalConfig
+from frappy.properties import Property
 
 
 class DispatcherStub:
@@ -445,6 +446,15 @@ def test_override():
     # inherit doc string
     assert Mod2.stop.description == Mod.stop.description
 
+    class Base(Module):
+        attr = Property('test property', FloatRange())
+
+    class Subclass(Base):
+        attr = Parameter('test parameter', FloatRange())
+
+    class SubSubclass(Subclass):  # pylint: disable=unused-variable
+        attr = 5.0
+
 
 def test_command_config():
     class Mod(Module):