Command prompt does not respect `VIRTUAL_ENV_DISABLE_PROMPT` when activating venv

[karrtikr]

Bug report

Bug description:

activate.bat does not know anything about VIRTUAL_ENV_DISABLE_PROMPT, unlike Activate.ps1, activate.fish & bash/zsh activate scripts.

CPython versions tested on:

CPython main branch

Operating systems tested on:

Windows

Linked PRs

• gh-109940: Respect VIRTUAL_ENV_DISABLE_PROMPT in activate.bat #151215
• [3.15] gh-109940: Respect VIRTUAL_ENV_DISABLE_PROMPT in activate.bat (GH-151215) #151225

[gaborbernat]

Confirmed, still present on main: activate.bat sets PROMPT=(...) %PROMPT% unconditionally, with no VIRTUAL_ENV_DISABLE_PROMPT check, so on Windows cmd the prefix is added regardless of the variable. It's the only CPython activator that ignores it — bash/zsh, fish, csh, and Activate.ps1 all gate the prompt on it.

virtualenv's batch activator gates both the prompt save and the prompt change on if not defined VIRTUAL_ENV_DISABLE_PROMPT (activate.bat L21-27). Wrapping the _OLD_VIRTUAL_PROMPT save and the PROMPT= line in the same check would fix it.