Parentheses escaping bug when running `pipenv shell`

[leohku]

Summary:

When running pipenv shell in POSIX (zsh), running /bin/activate will fail if there are parentheses in the virtualenv path due to the regex in _get_activate_script() (Line 53, pipenv/shells.py) not escaping parentheses properly.

How to reproduce the issue:

1. Create a new directory a ( )
2. Create .venv folder inside the directory
3. Run pipenv install in a ( )
4. Run pipenv shell. The issue should now be reproduced.
5. To verify, run pipenv shell again to confirm the improper activation.

What is expected to happen:

Step 4 successfully activates virtual environment without error return code (1).

What actually happens:

Step 4 output:

$ pipenv shell
Launching subshell in virtual environment...
 . /Users/leohku/a\ (\ )/.venv/bin/activate
zsh: no matches found: /Users/leohku/a ( )/.venv/bin/activate

Step 5 output:

$ pipenv shell
Shell for UNKNOWN_VIRTUAL_ENVIRONMENT already activated.
No action taken to avoid nested environments.

Environment:

pipenv, version 2020.11.15
running zsh on macOS Big Sur v11.1 x86