dask is timing out and so failing debci tests in testing on armhf,
which is blocking [re]migration back into testing.

1271s tests/test_distributed.py::test_futures_to_delayed_dataframe PASSED      [ 94%]
1273s tests/test_distributed.py::test_from_delayed_dataframe PASSED            [ 94%]
1279s tests/test_distributed.py::test_fused_blockwise_dataframe_merge[True] PASSED [ 94%]
10207s tests/test_distributed.py::test_fused_blockwise_dataframe_merge[False] autopkgtest [23:00:16]: ERROR: timed out on command "su -s /bin/bash debci -c set -e; exec /tmp/autopkgtest-lxc.fnv_8ew1/downtmp/wrapper.sh --artifacts=/tmp/autopkgtest-lxc.fnv_8ew1/downtmp/run-test-artifacts --chdir=/tmp/autopkgtest-lxc.fnv_8ew1/downtmp/build.f5B/src --env=AUTOPKGTEST_TESTBED_ARCH=armhf --env=AUTOPKGTEST_TEST_ARCH=armhf --env=DEB_BUILD_OPTIONS=parallel=8 --env=DEBIAN_FRONTEND=noninteractive --env=LANG=C.UTF-8 --unset-env=LANGUAGE --unset-env=LC_ADDRESS --unset-env=LC_ALL --unset-env=LC_COLLATE --unset-env=LC_CTYPE --unset-env=LC_IDENTIFICATION --unset-env=LC_MEASUREMENT --unset-env=LC_MESSAGES --unset-env=LC_MONETARY --unset-env=LC_NAME --unset-env=LC_NUMERIC --unset-env=LC_PAPER --unset-env=LC_TELEPHONE --unset-env=LC_TIME --script-pid-file=/tmp/autopkgtest_script_pid --source-profile --stderr=/tmp/autopkgtest-lxc.fnv_8ew1/downtmp/run-test-stderr --stdout=/tmp/autopkgtest-lxc.fnv_8ew1/downtmp/run-test-stdout --tmp=/tmp/autopkgtest-lxc.fnv_8ew1/downtmp/autopkgtest_tmp --make-executable=/tmp/autopkgtest-lxc.fnv_8ew1/downtmp/build.f5B/src/debian/tests/run-test -- /tmp/autopkgtest-lxc.fnv_8ew1/downtmp/build.f5B/src/debian/tests/run-test" (kind: test)
10207s autopkgtest [23:00:16]: test run-test: -----------------------]
10207s autopkgtest [23:00:16]: test run-test:  - - - - - - - - - - results - - - - - - - - - -
10208s run-test             FAIL timed out


We can't run the test right now in unstable because of Bug#1143509,
that's a different issue.