"?" Is displayed incorrectly in debug console when debug flask.

[linette-zyy]

Repro steps:

Pre-requesites:
Clone repro and run the setup script:
git clone https://github.com/qubitron/pydemo
cd pydemo
py -3 setup.py

In user settings add:
"python.jediEnabled": false

1. Open stackoverflow-flask folder
2. Select "Debug"
3. Select "Add Configuration…" in "DEBUG" dropdown menu
4. Customize the path in launch.json:
   
5. Set "DEBUG" to "Python:Flask"
   
   6.Start to debug and observe app starts in terminal, ctrl+click to open the app in the browser
6. Set breakpoint on line6 of main.py and then start to debug and refresh the browser page
7. Make sure breakpoint is hit and main.py works
8. Click "F10/F11/Shift+F11/stop" to verify debug works

Expected behaviour

The debug console display correct without incorrect symbol.

Actual behavior

"?" Is displayed incorrectly in debug console.

Test Environment

[int19h]

This is ptvsd 4 - can you please try the same with ptvsd 5, by following these instructions?