fix deprecated update according to parent

[troopa81]

revert part of #50

with #50 True is displayed instead of the deprecation message

(.venv) ➜  test git:(master) ✗ python test.py
/home/julien/myconf/sip-examples/deprecated/test/test.py:9: DeprecationWarning: Test constructor is deprecated: True
  a=Test()
/home/julien/myconf/sip-examples/deprecated/test/test.py:10: DeprecationWarning: Test.printTestDeprecated() is deprecated: True
  a.printTestDeprecated() # this is a comment

The PR proposes to :

• not update current item deprecated with parent if another more specific message exist on the current item
• Update current item with parent message and not True when there is no overloaded message defined on current item

[philthompson10]

Thanks. I'd rolled back all the changes to the file just to get PyQt working again.