fix: prepend virtualenv path rather than append

[kalvinnchau]

prepend virtualenv path rather than append

When using the

_.python.venv = { path = "{{env.MISE_DATA_DIR}}/python/venv", create = true }

Syntax with nested directories, I found that which python would report the most globally available .mise.toml virtualenv python rather than the more locally specific .mise.toml. The VIRTUAL_ENV environment variable would be set correctly however, causing a bit of confusion initially.

background

A minimal example:

❯ tree -a mise-example
mise-example
├── .mise.toml
└── sub
    ├── .mise.toml
    └── nest
        └── .mise.toml

# mise-example
[tools]
python = "3.11"

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

# mise-example.sub
[tools]
python = "3.9"

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

# mise-example.sub.nest
[tools]
python = "3.12"

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

And the output of PATH from the mise-example/sub/nest directory:

❯ echo $PATH

/Users/knc/.local/share/mise/python/venv/example/bin:/Users/knc/.local/share/mise/python/venv/sub/bin:/Users/knc/.local/share/mise/python/venv/nest/bin:...

[DEBUG] ARGS: /Users/knc/.local/bin/mise hook-env -s zsh
[DEBUG] Config {
    Config Files: [
        "~/stage/mise-example/sub/nest/.mise.toml",
        "~/stage/mise-example/sub/.mise.toml",
        "~/stage/mise-example/.mise.toml",
        "~/.config/mise/config.toml",
    ],
    Env: {
        "MISE_DATA_DIR": "/Users/knc/.local/share/mise",
        "MISE_POETRY_AUTO_INSTALL": "1",
        "VIRTUAL_ENV": "/Users/knc/.local/share/mise/python/venv/nest",
    },
    Path Dirs: [
        "/Users/knc/.local/share/mise/python/venv/example/bin",
        "/Users/knc/.local/share/mise/python/venv/sub/bin",
        "/Users/knc/.local/share/mise/python/venv/nest/bin",
    ],
}

changes

This change inserts the found virtualenv to the front of the env_paths instead, resulting in the Path Dirs in the DEBUG output to be flipped and showing the correct python version when running which python:

[DEBUG] Config {
...
    Path Dirs: [
        "/Users/kchau/.local/share/mise/python/venv/nest/bin",
        "/Users/kchau/.local/share/mise/python/venv/sub/bin",
        "/Users/kchau/.local/share/mise/python/venv/example/bin",
    ],
}

I added an e2e test to create a subdirectory to verify this, as well as a unit test. I verified the new e2e test fails on the current main without the change:

mise creating venv at: ~/.mise/e2e/venv
mise all runtimes are installed
mise creating venv at: ~/.mise/e2e/subvenv
Expected '/root/.mise/e2e/subvenv/bin/python' but got '/root/.mise/e2e/venv/bin/python'
::error file=e2e/test_python::E2E Test Failed (code: 1)

I'm not sure I completely like the unit test having to rely on the cwd and / directories to pass - but I didn't see any test scaffolding / mocks to ensure a Path exists. Let me know how you'd want this to change if anything.