Inheritance not working with non-abstract base methods

[bminixhofer]

Environment

• Pythonnet version: 2.3.0
• Python version: 3.6.3
• Operating System: Windows 10

Details

• Describe what you were trying to get done.

This issue comes from this StackOverflow question.
I was trying to use a C# DLL which has a class that overrides a non-abstract method of its parent class. Although the new method should be used, pythonnet still calls the parent method. The code for a minimal DLL to reproduce this problem looks like this:

using System;

namespace InheritanceTest
{
    public class BaseClass
    {
        public bool Transmit()
        {
            throw new NotImplementedException();
        }
    }

    public class InheritedClass: BaseClass
    {
        public new bool Transmit()
        {
            Console.WriteLine("Success!");
            return true;
        }
    }
}

• What commands did you run to trigger this issue? If you can provide a
  Minimal, Complete, and Verifiable example
  this will help us understand the issue.

In the following python code, BaseClass.Transmit should be called when BaseClass is directly instantiated and InheritedClass.Transmit when InheritedClass is instantiated. However, BaseClass.Transmit is called both times.

## setup
import clr
import os

clr.AddReference(os.getcwd() + '\\InheritanceTest.dll')
import InheritanceTest

## method test

base_class = InheritanceTest.BaseClass()
base_class.Transmit() # throws a NotImplementedException as expected

inherited_class = InheritanceTest.InheritedClass()
inherited_class.Transmit() # still throws a NotImplementedException, although it should call InheritedClass.Transmit

[den-run-ai]

@bminixhofer related #552?

[bminixhofer]

@denfromufa It seems to me that #552 is the exact same issue (although worded a little strangely in my opinion, i wasn't able to find it when first researching the problem).
#756 fixes #552 too.