fix(env): run local commands through bash

[dannyward630]

Summary

Fixes #829.

LocalEnvironment advertised and prompted bash commands, but executed them via subprocess.Popen(..., shell=True). On Debian/Ubuntu, Python uses /bin/sh for shell=True, and /bin/sh is commonly dash, so bash-only syntax such as process substitution fails even though the tool is named bash.

This changes local command execution to use a configurable interpreter, defaulting to bash -lc, matching the Docker backend's default interpreter behavior more closely while preserving the existing timeout/process-group handling.

Validation

• .venv/bin/python -m pytest tests/environments/test_local.py
• .venv/bin/ruff check src/minisweagent/environments/local.py tests/environments/test_local.py
• git diff --check

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[Copilot]

Pull request overview

This PR fixes the LocalEnvironment “bash” tool to actually execute commands with Bash (instead of /bin/sh via shell=True, which is often dash on Debian/Ubuntu), aligning behavior more closely with the Docker environment and enabling bash-only syntax like process substitution.

Changes:

• Add a configurable interpreter to LocalEnvironmentConfig, defaulting to ["bash", "-lc"].
• Switch local command execution from subprocess.Popen(..., shell=True) to invoking the configured interpreter directly.
• Add test coverage ensuring bash-only syntax works by default (skipped on Windows).

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
src/minisweagent/environments/local.py	Introduces a configurable interpreter (default bash -lc) and runs commands through it instead of /bin/sh via shell=True.
tests/environments/test_local.py	Extends config default assertions and adds a bash-only syntax test to prevent regressions.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

Files with missing lines	Coverage Δ
src/minisweagent/environments/local.py	100.00% <100.00%> (ø)

... and 1 file with indirect coverage changes

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[dannyward630]

Closing in favor of #870, which implements the maintainer's shell-agnostic prompt/tool-description approach for #829.

[klieret]

still thinking about this, your PR is also very clean (thx!), I'm just still wondering if just prefixing bash -lc to the Popen is fully equivalent or if there's any edge cases (I guess popen handles all the escaping etc, but is there more that could break)

[klieret]

The one thing I don't like with this, is that this will probably not work out of the box on some systems...