Make Git-based tests independent of user Git configuration

[Widthdom]

Summary

Tests that create temporary Git repositories inherit the executing user’s global Git configuration. In an environment with commit.gpgsign=true, test commits can request signing credentials or a passphrase and then fail or hang.

Proposed approach

• Disable commit signing in each test repository with local configuration, or pass the setting explicitly to every test Git command.
• Isolate Git configuration directories or environment variables per test where appropriate.
• Never readjust or overwrite the user’s global Git configuration.
• Centralize test Git invocation and initialization in a shared helper to prevent configuration gaps.
• Add regression coverage that simulates a global commit.gpgsign=true setting.
• Review other inherited Git settings that could affect deterministic test behavior.

Acceptance criteria

• The full test suite runs non-interactively when global commit.gpgsign=true is set.
• Neither GPG nor SSH signing prompts appear during tests.
• Tests do not modify the user’s global Git configuration.
• Local and GitHub Actions runs produce the same result.
• Git-based tests use a clearly defined common initialization path.