bootstrap_impl=script does not work with 3.14.0b2

[aignas]

When adding #2969 I noticed that the 3.14.0b2 is failing the //tests/toolchains/ when using the script bootstrap. It seems that the sys.path setup is not working and the bazel runfiles library cannot be found.

Not sure why this happens.

$ bazel test //tests/toolchains:python_3.14.0b2_test --//python/config_settings:bootstrap_impl=script
INFO: Analyzed target //tests/toolchains:python_3.14.0b2_test (86 packages loaded, 10547 targets configured).
FAIL: //tests/toolchains:python_3.14.0b2_test (Exit 1) (see /home/aignas/.cache/bazel/_bazel_aignas/6f0de8c9128ee8d5dbf27ba6dcc48bdd/execroot/_main/bazel-out/k8-fastbuild-ST-6c118783b860/testlogs/tests/toolchains/python_3.14.0b2_test/test.log)
INFO: From Testing //tests/toolchains:python_3.14.0b2_test:
==================== Test output for //tests/toolchains:python_3.14.0b2_test:
<frozen site>:101: RuntimeWarning: Unexpected value in sys.prefix, expected /home/aignas/.cache/bazel/_bazel_aignas/6f0de8c9128ee8d5dbf27ba6dcc48bdd/sandbox/linux-sandbox/1/execroot/_main/bazel-out/k8-fastbuild-ST-6c118783b860/bin/tests/toolchains/python_3.14.0b2_test.runfiles/_main/tests/toolchains/_python_3.14.0b2_test.venv, got /home/aignas/.cache/bazel/_bazel_aignas/6f0de8c9128ee8d5dbf27ba6dcc48bdd/execroot/_main/external/+python+python_3_14_0b2_x86_64-unknown-linux-gnu
<frozen site>:101: RuntimeWarning: Unexpected value in sys.exec_prefix, expected /home/aignas/.cache/bazel/_bazel_aignas/6f0de8c9128ee8d5dbf27ba6dcc48bdd/sandbox/linux-sandbox/1/execroot/_main/bazel-out/k8-fastbuild-ST-6c118783b860/bin/tests/toolchains/python_3.14.0b2_test.runfiles/_main/tests/toolchains/_python_3.14.0b2_test.venv, got /home/aignas/.cache/bazel/_bazel_aignas/6f0de8c9128ee8d5dbf27ba6dcc48bdd/execroot/_main/external/+python+python_3_14_0b2_x86_64-unknown-linux-gnu
Traceback (most recent call last):
  File "/home/aignas/.cache/bazel/_bazel_aignas/6f0de8c9128ee8d5dbf27ba6dcc48bdd/sandbox/linux-sandbox/1/execroot/_main/bazel-out/k8-fastbuild-ST-6c118783b860/bin/tests/toolchains/python_3.14.0b2_test.runfiles/_main/tests/toolchains/_python_3.14.0b2_test_stage2_bootstrap.py", line 474, in <module>
    main()
    ~~~~^^
  File "/home/aignas/.cache/bazel/_bazel_aignas/6f0de8c9128ee8d5dbf27ba6dcc48bdd/sandbox/linux-sandbox/1/execroot/_main/bazel-out/k8-fastbuild-ST-6c118783b860/bin/tests/toolchains/python_3.14.0b2_test.runfiles/_main/tests/toolchains/_python_3.14.0b2_test_stage2_bootstrap.py", line 468, in main
    _run_py_path(main_filename, args=sys.argv[1:])
    ~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/aignas/.cache/bazel/_bazel_aignas/6f0de8c9128ee8d5dbf27ba6dcc48bdd/sandbox/linux-sandbox/1/execroot/_main/bazel-out/k8-fastbuild-ST-6c118783b860/bin/tests/toolchains/python_3.14.0b2_test.runfiles/_main/tests/toolchains/_python_3.14.0b2_test_stage2_bootstrap.py", line 284, in _run_py_path
    runpy.run_path(main_filename, run_name="__main__")
    ~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "<frozen runpy>", line 287, in run_path
  File "<frozen runpy>", line 98, in _run_module_code
  File "<frozen runpy>", line 88, in _run_code
  File "/home/aignas/.cache/bazel/_bazel_aignas/6f0de8c9128ee8d5dbf27ba6dcc48bdd/sandbox/linux-sandbox/1/execroot/_main/bazel-out/k8-fastbuild-ST-6c118783b860/bin/tests/toolchains/python_3.14.0b2_test.runfiles/_main/tests/toolchains/python_toolchain_test.py", line 8, in <module>
    from python.runfiles import runfiles
ModuleNotFoundError: No module named 'python'
================================================================================
INFO: Found 1 test target...
Target //tests/toolchains:python_3.14.0b2_test up-to-date:
  bazel-bin/tests/toolchains/python_3.14.0b2_test
INFO: Elapsed time: 43.869s, Critical Path: 1.32s
INFO: 12 processes: 10 internal, 2 linux-sandbox.
INFO: Build completed, 1 test FAILED, 12 total actions
//tests/toolchains:python_3.14.0b2_test                                  FAILED in 0.7s
  /home/aignas/.cache/bazel/_bazel_aignas/6f0de8c9128ee8d5dbf27ba6dcc48bdd/execroot/_main/bazel-out/k8-fastbuild-ST-6c118783b860/testlogs/tests/toolchains/python_3.14.0b2_test/test.log

Executed 1 out of 1 test: 1 fails locally.

[rickeylev]

Hrm. It looks like something changed in 3.14's getpath.py and/or site.py.

[rickeylev]

This seems to be caused by python/cpython#126987

I've filed python/cpython#135773

3.14 is still beta with a couple months to final, so hopefully we can get something from upstream before 3.14 is released. So far, I haven't been able to find a workaround (other than abandoning a build-time venv, which would really suck).