v2026.2.18: mise exec -- python3 ignores venv at runtime

[erichoracek]

After upgrading to mise v2026.2.18, mise exec -- python3 appears to resolve python3 to the repo virtualenv path, but the process that actually runs is the base mise-managed Python interpreter.

This breaks workflows that install Python deps into .venv and then run scripts via mise exec -- python3 ....

Environment

• macOS arm64
• Reproducible with release binaries:
  • v2026.2.17 works
  • v2026.2.18 fails
• Repo config includes:

[env]
_.python.venv = { path = ".venv", create = true }

Observed behavior

With v2026.2.18:

• mise exec -- which python3 prints .venv/bin/python3
• but mise exec -- python3 ... runs the base mise Python (~/.local/share/mise/installs/python/.../bin/python3)
• venv-only packages are not available

Expected behavior

mise exec -- python3 ... should execute the same interpreter shown by which python3 (the repo venv interpreter), so packages installed into .venv are importable.