opening venv in windows bug

[YoniChechik]

Environment data

• VS Code version: 1.37.1
• Extension version (available under the Extensions sidebar): 2019.8.30787
• OS and version: windows 10
• Python version (& distribution if applicable, e.g. Anaconda): python 3.7.1
• Type of virtual environment used (N/A | venv | virtualenv | conda | ...): venv
• Relevant/affected Python packages and their versions: -
• Jedi or Language Server? (i.e. what is "python.jediEnabled" set to; more info How to update the language server to the latest stable version #3977): -

Expected behavior

F5->Python file should run the script in default env on windows when new terminal is opened with ".../activate.ps1"

Actual behavior

it runs ".../activate.bat" which doesn't initialize the current env

Steps to reproduce:

F5->Python file on a new window of vscode

[DonJayamanne]

Dup of #6928