writing tests for 
        "The bug appeared when removing two extensions methods (from the same extending package)
for a   
    same class. in RPackage >> removeMethod: , when removing an extension method, we were
telling the 
    organizer to remove the extending package for the class concerned. This was wrong,
because even if one 
    extension from this package has been removed, some others can still exist. And the
organizer should keep 
    the this package as extending package for the class. So removing the first extension
method worked 
    correctly, but then removing a second or more methods from the same package was raising
some errors "