Launch a SubModule

[jkassismz]

Environment data

• PTVSD version: ms-python.python-2019.3.6139
• OS and version: MacOS
• Python version (& distribution if applicable, e.g. Anaconda): 3.6.5
• Using VS Code or Visual Studio: VS Code (or CLI)

Actual behavior

Cannot launch a main.py in a submodule...
ptvsd complains that the module is not found

Expected behavior

Launching a main.py method in a submodule works

Steps to reproduce:

1. Create a main.py in a submodule.
2. Create a launch configuration that runs it with "module": "root.sub" or use the CLI:
   /projects/pybot/venv/bin/python /Users/jkassis/.vscode/extensions/ms-python.python-2019.3.6139/pythonFiles/ptvsd_launcher.py --default --host 127.0.0.1 --port 51251 -m commands.pybot
3. Run it.
4. Watch the magic.
5. Move it up one level
6. Run...
   /projects/pybot/venv/bin/python /Users/jkassis/.vscode/extensions/ms-python.python-2019.3.6139/pythonFiles/ptvsd_launcher.py --default --host 127.0.0.1 --port 51251 -m pybot
7. Watch the magic.