vscode-python: Can't autodetect pipenv on 2018.2.1

Environment data

• VS Code version: 1.21.0: 2018 Feb
• Extension version (available under the Extensions sidebar): 2018.2.1
• OS and version: macOs High Sierra 10.13.3
• Python version: CPython 3.6.4
• Type of virtual environment used (if applicable): pipenv
• Relevant/affected Python packages and their versions: pipenv==11.3.2

Actual behavior

When open a project with Pipfile, the interpreter is bare Python 3.6.4

Expected behavior

When open a project with Pipfile, the interpreter will be autodetected as Python3.6.4(pipenv) and uses the virtualenv created by pipenv

Steps to reproduce:

1. pipenv install to create a virtualenv for requests_html
2. Open the project in VSCode

Logs

Output for Python in the Output panel (View→Output, change the drop-down the upper-right of the Output panel to Python)

Only linting messages

Output from Console under the Developer Tools panel (toggle Developer Tools on under Help)

[Extension Host] (node:33660) DeprecationWarning: os.tmpDir() is deprecated. Use os.tmpdir() instead.
t.log @ workbench.main.js:sourcemap:257