Double parenthesis on virtual environment shell prompt of Python 3.12.13

A reproducible but harmless bug

Photo by Erwan Hesry on Unsplash

After activated virtual environment created using Python 3.12 on MacOS it was observed that there is double parenthesis in the prompt (Viridi, 2026). Further discussion only produced sugggestions to overcome the harmless bug (GPT-5.5, 2026). Fortunately, the bug is documented (IterableTrucks, 2025) but not fixed since the version no longer allows bugfixes (StanFromIreland, 2025).

Python 3.9.6

This is the version provided by macOS Sequoia (Apple, 2024).

envs % source base/bin/activate
(base) envs % python - version
Python 3.9.6
(base) envs % deactivate
envs %

Python 3.12.13

This version is installed using Homebrew (Homebrew, 2026).

envs % source tf/bin/activate 
((tf) ) envs % python - version 
Python 3.12.13
((tf) ) envs % deactivate
envs %

Experiment

Two additional virtual environments are further created and the bug is reproducible and consistent.

envs % source test/bin/activate
((test) ) envs % python - version
Python 3.12.13
((test) ) envs % deactivate
envs %
envs % source test2/bin/activate
(test2) envs % python - version
Python 3.9.6
(test2) envs % deactivate
envs %

Processes of creating both virtual environments are not shown.

Summaries

• Double parenthesis on the virtual environment prompt created using Python 3.12.13 is reported.
• The bug is harmless and not fixed.
• The bug is reproducible and consistent.

Refs

• Sparisoma Viridi, “Steps to install Python on macOS”, Medium, 23 May 2026, url https://medium.com/p/08e2260e8c24 [20260524].
• GPT-5.5, “Virtual Environment Prompt Differences”, ChatGPT, 23 May 2026, url https://chatgpt.com/share/6a116d8c-2e08-83ec-90b7-25484621f0a6 [20260523].
• IterableTrucks, “Double parenthesis in activated venv generated by Python 3.12.10”, python/cpython GitHub Issues, 10 Apr 2025, url https://github.com/python/cpython/issues/132361 [20260524].
• StanFromIreland, “Double parenthesis in activated venv generated by Python 3.12.10”, python/cpython GitHub Issues, 15 Apr 2025, url https://github.com/python/cpython/issues/132361#issuecomment-2806729854 [20260524].
• -, “macOS Sequoia takes productivity and intelligence on Mac to new heights”, Apple Newsroom, 10 Jun 2024, url https://www.apple.com/newsroom/2024/06/macos-sequoia-takes-productivity-and-intelligence-on-mac-to-new-heights/ [20260524].
• Max Howell, Rémi Prévost, Mike McQuaid, Danielle Lalonde, “Homebrew: The Missing Package Manager for macOS (or Linux)”, Homebrew, 2026, url https://brew.sh [20260524].