[core] Stop parent git repos from breaking ESP-IDF/PlatformIO builds (#16994)

tests/unit_tests/test_platformio_toolchain.py

@@ -304,6 +304,11 @@ def test_run_platformio_cli_sets_environment_variables(
         )
         assert "PLATFORMIO_LIBDEPS_DIR" in os.environ
         assert "PYTHONWARNINGS" in os.environ
+        # Caps git's upward search at the config dir so an uninitialized or
+        # corrupt parent git repo can't break the framework's `git describe`.
+        assert str(CORE.config_dir) in os.environ["GIT_CEILING_DIRECTORIES"].split(
+            os.pathsep
+        )
 
         # Check command was called correctly — runs PlatformIO as a subprocess
         # via the esphome.platformio.runner entry point.