test(cache-conf): isolate the env the handler reads through setdefault

0d2fadce0c simplified this test and dropped the env patch the old one carried. EnvBuilder.setdefault keeps whatever os.environ already holds, and the test container injects INFINITO_CACHE_PACKAGE_FRONTEND_CONF through BASH_ENV, so the assertion compared the worktree path against its own temp directory and only failed inside the container.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

tests/unit/python/utils/env/handlers/infinito/test_cache_conf.py

@@ -2,9 +2,11 @@
 
 from __future__ import annotations
 
+import os
 import unittest
 from pathlib import Path
 from tempfile import TemporaryDirectory
+from unittest.mock import patch
 
 from utils.env.builder import BuildContext, EnvBuilder
 from utils.env.handlers.infinito.cache import conf as handler
@@ -26,6 +28,7 @@ class TestApply(unittest.TestCase):
         self.addCleanup(self._tmp.cleanup)
         self.root = Path(self._tmp.name).resolve()
 
+    @patch.dict(os.environ, {handler.KEY: ""}, clear=False)
     def test_the_map_is_rendered_in_the_checkout_that_builds_it(self) -> None:
         eb = EnvBuilder()