Automatic Python environment activation does not select the correct environment with a multiproject workspace

[mr-katsini]

Environment data

• VS Code version: 1.32.1
• Extension version (available under the Extensions sidebar): 1.32.1
• OS and version: OSX: 10.14.3
• Python version (& distribution if applicable, e.g. Anaconda): 3.7.0
• Type of virtual environment used (N/A | venv | virtualenv | conda | ...): virtualenv
• Relevant/affected Python packages and their versions: XXX

Expected behaviour

Opening a terminal for a multiproject workspace should also set the python environment activation for the project selected.

Actual behaviour

When opening a terminal on a multiproject workspace, the terminal always defaults the source to the virtualenv of the first project in the workspace tree.

Ie.

Projects:
/project1/ -> venv path ..virtualenvs/project1/bin/activate
/project2/ -> venv path ..virtualenvs/project2/bin/activate

When opening a new terminal and selecting project2, the terminal behaviour is as follows

cd /project2/
source virtualenvs/project1/bin/activate

Steps to reproduce:

1. Add multiple python projects to workspace
2. Configure environment python paths for each project
3. Open an integrated terminal for any python project and it will use the python path for the first project in the tree

[DonJayamanne]

Duplicate of #3325