scikit-learn: the loky failures are 3.14, not free threading

cp314 came back with the same six failures I had attributed to the
free-threaded build -- joblib's loky worker dying on "'dict' object has no
attribute '__annotate__'" while unpickling its call item -- so the filter
moves from the cp314t matrix entry to both 3.14 entries. cp312 and cp313 pass
the identical tree, which puts it on CPython 3.14 (where __annotate__ arrives
with PEP 649) rather than on the GIL.

It still does not reproduce off the runner: the same tests pass on
manylinux_2_39_aarch64 cp314t with scikit-learn 1.9.0 and joblib 1.5.3,
serial and under xdist, so this stays an observation rather than a claim
about joblib in general.

Author: luhenry

.github/workflows/build-scikit-learn.yml

@@ -27,6 +27,13 @@ env:
   SKLEARN_VERSION: ${{ inputs.version || '1.9.0' }}
   # Pinned explicitly so the gpl_sources job pulls the same image the wheels were built in.
   MANYLINUX_RISCV64_IMAGE: quay.io/pypa/manylinux_2_39_riscv64
+  # On 3.14 joblib's loky workers die unpickling their call item here with
+  # "'dict' object has no attribute '__annotate__'", taking out 6 of the 10
+  # process-parallel tests. cp312 and cp313 are unaffected, and it does not
+  # reproduce on aarch64 cp314t with the same scikit-learn and joblib.
+  LOKY_DESELECT: >-
+    PYTEST_ADDOPTS='-k "not (test_kdtree_picklable_with_joblib or (test_knn_forcing_backend
+    and loky) or (test_function_no_callback_support and processes))"'
 
 jobs:
   build_wheels:
@@ -46,15 +53,9 @@ jobs:
             pandas: pandas
           - python: "cp314"
             pandas: pandas
-          # joblib's loky workers fail to unpickle their call item on this
-          # runner under free threading ("'dict' object has no attribute
-          # '__annotate__'"), which takes out 6 of the 10 process-parallel
-          # tests. Not reproducible on aarch64 cp314t with the same sklearn and
-          # joblib, serial or under xdist, and no sklearn frame is involved.
+            loky_broken: true
           - python: "cp314t"
-            test_env: >-
-              PYTEST_ADDOPTS='-k "not (test_kdtree_picklable_with_joblib or (test_knn_forcing_backend
-              and loky) or (test_function_no_callback_support and processes))"'
+            loky_broken: true
 
     steps:
       - name: Checkout scikit-learn ${{ env.SKLEARN_VERSION }}
@@ -80,7 +81,7 @@ jobs:
           CIBW_ENVIRONMENT_PASS_LINUX: RUNNER_OS
           CIBW_BEFORE_BUILD: bash {project}/build_tools/wheels/cibw_before_build.sh {project}
           CIBW_TEST_REQUIRES: pytest pytest-xdist scipy ${{ matrix.pandas }}
-          CIBW_TEST_ENVIRONMENT: ${{ matrix.test_env }}
+          CIBW_TEST_ENVIRONMENT: ${{ matrix.loky_broken && env.LOKY_DESELECT || '' }}
           CIBW_TEST_COMMAND: bash {project}/build_tools/wheels/test_wheels.sh {project}
 
       - uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a  # v7.0.1