[Bazel CI] Test Failure: Python Toolchain Regression - Windows Runtime Bootstrap Failures (Exit 2)

CI: https://buildkite.com/bazel/bazel-at-head-plus-downstream/builds/5268#019c45ba-8186-4bd8-adda-218d5f0a1bdf

Platform: Default (Windows)

Logs:

```
(04:16:58) [297 / 612] 164 / 540 tests, 1 failed; 30 actions, 19 running; last test: //tests/bootstrap_impls:run_binary_zip_no_test
--
Testing //tests/bootstrap_impls:run_binary_zip_no_test; 17s local, remote-cache
(04:17:25) FAIL: //tests/runtime_env_toolchain:bootstrap_script_test (Exit 2) (see C:/b/xe3bomgm/execroot/_main/bazel-out/x64_windows-fastbuild-ST-1b13a798666d/testlogs/tests/runtime_env_toolchain/bootstrap_script_test/test_attempts/attempt_1.log)
(04:17:25) [458 / 677] 272 / 540 tests, 1 failed; 30 actions, 21 running; last test: //tests/pypi/parse_requirements:test_multi_os
(04:17:27) FAIL: //tests/runtime_env_toolchain:bootstrap_script_test (Exit 2) (see C:/b/xe3bomgm/execroot/_main/bazel-out/x64_windows-fastbuild-ST-1b13a798666d/testlogs/tests/runtime_env_toolchain/bootstrap_script_test/test_attempts/attempt_2.log)
(04:17:33) FAIL: //tests/runtime_env_toolchain:bootstrap_script_test (Exit 2) (see C:/b/xe3bomgm/execroot/_main/bazel-out/x64_windows-fastbuild-ST-1b13a798666d/testlogs/tests/runtime_env_toolchain/bootstrap_script_test/test.log)
FAILED: //tests/runtime_env_toolchain:bootstrap_script_test (Summary)
(04:17:42) FAIL: //tests/exec_toolchain_matching:test_exec_matches_target_python_version (Exit 1) (see C:/b/xe3bomgm/execroot/_main/bazel-out/x64_windows-fastbuild/testlogs/tests/exec_toolchain_matching/test_exec_matches_target_python_version/test_attempts/attempt_1.log)
(04:17:42) [563 / 732] 342 / 540 tests, 2 failed; 29 actions, 19 running; last test: //tests/toolchains:python_3.14.2_test
Testing //tests/pypi/config_settings:test_legacy_with_constraint_values; 0s local, remote-cache
(04:17:43) FAIL: //tests/exec_toolchain_matching:test_exec_matches_target_python_version (Exit 1) (see C:/b/xe3bomgm/execroot/_main/bazel-out/x64_windows-fastbuild/testlogs/tests/exec_toolchain_matching/test_exec_matches_target_python_version/test_attempts/attempt_2.log)
(04:17:43) FAIL: //tests/runtime_env_toolchain:toolchain_runs_test (Exit 2) (see C:/b/xe3bomgm/execroot/_main/bazel-out/x64_windows-fastbuild-ST-a20f7ca3e2cb/testlogs/tests/runtime_env_toolchain/toolchain_runs_test/test_attempts/attempt_1.log)
(04:17:43) [577 / 732] 356 / 540 tests, 2 failed; 30 actions, 25 running; last test: //tests/pypi/select_whl:test_pytags_all_possible
Testing //tests/repl:repl_without_dep_test; 43s local, remote-cache
(04:17:43) FAIL: //tests/exec_toolchain_matching:test_exec_matches_target_python_version (Exit 1) (see C:/b/xe3bomgm/execroot/_main/bazel-out/x64_windows-fastbuild/testlogs/tests/exec_toolchain_matching/test_exec_matches_target_python_version/test.log)
FAILED: //tests/exec_toolchain_matching:test_exec_matches_target_python_version (Summary)
(04:17:43) [583 / 732] 363 / 540 tests, 3 failed; 30 actions, 24 running; last test: ...hain_matching:test_exec_matches_target_python_version
```

Culprit:

Steps:

git clone https://github.com/bazel-contrib/rules_python.git
git reset 0f4ff60a1727300e1bace6233e566076736e9f15 --hard
export USE_BAZEL_VERSION=f1be9ccfa5e5144f28e59686a03fd4a2df23f623
bazel build //...

CC Greenteam @salmasamy

コミット 0f4ff60a1727300e1bace6233e566076736e9f15 の失敗を、USE_BAZEL_VERSION=f1be9ccfa5e5144f28e59686a03fd4a2df23f623 および bazel build //... を使って再現します。まず tests/runtime_env_toolchain:bootstrap_script_test、tests/runtime_env_toolchain:toolchain_runs_test、tests/exec_toolchain_matching:test_exec_matches_target_python_version のログから始めます。これらの Windows チェックがリグレッションなしでパスすれば完了です。

索引モデルが issue の本文から書いたものです。