test_concurrent_futures.test_interpreter_pool failed with "Fatal Python error: PyMutex_Unlock: unlocking mutex that is not locked" on RISC-V 64-bit Ubuntu 3.15 #159121

0:31:43 load avg: 8.56 [351/557/1] test.test_concurrent_futures.test_interpreter_pool worker non-zero exit code (Exit code -6 (SIGABRT)) -- running (2): test_zipfile (4 min 59 sec), test.test_multiprocessing_spawn.test_manager (35.7 sec)
test_default_executor (test.test_concurrent_futures.test_interpreter_pool.AsyncioTest.test_default_executor) ... ok
test_run_in_executor (test.test_concurrent_futures.test_interpreter_pool.AsyncioTest.test_run_in_executor) ... ok
test_run_in_executor_cancel (test.test_concurrent_futures.test_interpreter_pool.AsyncioTest.test_run_in_executor_cancel) ... ok
test_blocking (test.test_concurrent_futures.test_interpreter_pool.InterpreterPoolExecutorTest.test_blocking) ... ok
test_blocking_with_limited_workers (test.test_concurrent_futures.test_interpreter_pool.InterpreterPoolExecutorTest.test_blocking_with_limited_workers) ...

Fatal Python error: PyMutex_Unlock: unlocking mutex that is not locked
Python runtime state: initialized

Thread 0x0000003fddefb160 [InterpreterPool] (most recent call first):
  File "/var/lib/buildbot/workers/rise-riscv64-4/3.15.rise-riscv64-4/build/Lib/concurrent/interpreters/__init__.py", line 220 in _call
  File "/var/lib/buildbot/workers/rise-riscv64-4/3.15.rise-riscv64-4/build/Lib/concurrent/interpreters/__init__.py", line 238 in call
  File "/var/lib/buildbot/workers/rise-riscv64-4/3.15.rise-riscv64-4/build/Lib/concurrent/futures/interpreter.py", line 84 in run
  File "/var/lib/buildbot/workers/rise-riscv64-4/3.15.rise-riscv64-4/build/Lib/concurrent/futures/thread.py", line 86 in run
  File "/var/lib/buildbot/workers/rise-riscv64-4/3.15.rise-riscv64-4/build/Lib/concurrent/futures/thread.py", line 119 in _worker
  File "/var/lib/buildbot/workers/rise-riscv64-4/3.15.rise-riscv64-4/build/Lib/threading.py", line 1160 in run
  File "/var/lib/buildbot/workers/rise-riscv64-4/3.15.rise-riscv64-4/build/Lib/threading.py", line 1218 in _bootstrap_inner
  File "/var/lib/buildbot/workers/rise-riscv64-4/3.15.rise-riscv64-4/build/Lib/threading.py", line 1180 in _bootstrap

Thread 0x0000003fdd2fa160 [InterpreterPool] (most recent call first):
  File "/var/lib/buildbot/workers/rise-riscv64-4/3.15.rise-riscv64-4/build/Lib/concurrent/interpreters/__init__.py", line 220 in _call
  File "/var/lib/buildbot/workers/rise-riscv64-4/3.15.rise-riscv64-4/build/Lib/concurrent/interpreters/__init__.py", line 238 in call
  File "/var/lib/buildbot/workers/rise-riscv64-4/3.15.rise-riscv64-4/build/Lib/concurrent/futures/interpreter.py", line 84 in run
  File "/var/lib/buildbot/workers/rise-riscv64-4/3.15.rise-riscv64-4/build/Lib/concurrent/futures/thread.py", line 86 in run
  File "/var/lib/buildbot/workers/rise-riscv64-4/3.15.rise-riscv64-4/build/Lib/concurrent/futures/thread.py", line 119 in _worker
  File "/var/lib/buildbot/workers/rise-riscv64-4/3.15.rise-riscv64-4/build/Lib/threading.py", line 1160 in run
  File "/var/lib/buildbot/workers/rise-riscv64-4/3.15.rise-riscv64-4/build/Lib/threading.py", line 1218 in _bootstrap_inner
  File "/var/lib/buildbot/workers/rise-riscv64-4/3.15.rise-riscv64-4/build/Lib/threading.py", line 1180 in _bootstrap

Thread 0x0000003fdf7fe160 [InterpreterPool] (most recent call first):
  File "/var/lib/buildbot/workers/rise-riscv64-4/3.15.rise-riscv64-4/build/Lib/concurrent/interpreters/__init__.py", line 220 in _call
  File "/var/lib/buildbot/workers/rise-riscv64-4/3.15.rise-riscv64-4/build/Lib/concurrent/interpreters/__init__.py", line 238 in call
  File "/var/lib/buildbot/workers/rise-riscv64-4/3.15.rise-riscv64-4/build/Lib/concurrent/futures/interpreter.py", line 84 in run
  File "/var/lib/buildbot/workers/rise-riscv64-4/3.15.rise-riscv64-4/build/Lib/concurrent/futures/thread.py", line 86 in run
  File "/var/lib/buildbot/workers/rise-riscv64-4/3.15.rise-riscv64-4/build/Lib/concurrent/futures/thread.py", line 119 in _worker
  File "/var/lib/buildbot/workers/rise-riscv64-4/3.15.rise-riscv64-4/build/Lib/threading.py", line 1160 in run
  File "/var/lib/buildbot/workers/rise-riscv64-4/3.15.rise-riscv64-4/build/Lib/threading.py", line 1218 in _bootstrap_inner
  File "/var/lib/buildbot/workers/rise-riscv64-4/3.15.rise-riscv64-4/build/Lib/threading.py", line 1180 in _bootstrap

Thread 0x0000003fdffff160 [InterpreterPool] (most recent call first):
  File "/var/lib/buildbot/workers/rise-riscv64-4/3.15.rise-riscv64-4/build/Lib/concurrent/interpreters/__init__.py", line 220 in _call
  File "/var/lib/buildbot/workers/rise-riscv64-4/3.15.rise-riscv64-4/build/Lib/concurrent/interpreters/__init__.py", line 238 in call
  File "/var/lib/buildbot/workers/rise-riscv64-4/3.15.rise-riscv64-4/build/Lib/concurrent/futures/interpreter.py", line 84 in run
  File "/var/lib/buildbot/workers/rise-riscv64-4/3.15.rise-riscv64-4/build/Lib/concurrent/futures/thread.py", line 86 in run
  File "/var/lib/buildbot/workers/rise-riscv64-4/3.15.rise-riscv64-4/build/Lib/concurrent/futures/thread.py", line 119 in _worker
  File "/var/lib/buildbot/workers/rise-riscv64-4/3.15.rise-riscv64-4/build/Lib/threading.py", line 1160 in run
  File "/var/lib/buildbot/workers/rise-riscv64-4/3.15.rise-riscv64-4/build/Lib/threading.py", line 1218 in _bootstrap_inner
  File "/var/lib/buildbot/workers/rise-riscv64-4/3.15.rise-riscv64-4/build/Lib/threading.py", line 1180 in _bootstrap

Current thread 0x0000003fef9e0020 [python] (most recent call first):
  File "/var/lib/buildbot/workers/rise-riscv64-4/3.15.rise-riscv64-4/build/Lib/concurrent/interpreters/_queues.py", line 261 in get
  File "/var/lib/buildbot/workers/rise-riscv64-4/3.15.rise-riscv64-4/build/Lib/test/test_concurrent_futures/test_interpreter_pool.py", line 425 in test_blocking_with_limited_workers
  File "/var/lib/buildbot/workers/rise-riscv64-4/3.15.rise-riscv64-4/build/Lib/unittest/case.py", line 637 in _callTestMethod
  File "/var/lib/buildbot/workers/rise-riscv64-4/3.15.rise-riscv64-4/build/Lib/unittest/case.py", line 691 in run
  File "/var/lib/buildbot/workers/rise-riscv64-4/3.15.rise-riscv64-4/build/Lib/unittest/case.py", line 747 in __call__
  File "/var/lib/buildbot/workers/rise-riscv64-4/3.15.rise-riscv64-4/build/Lib/unittest/suite.py", line 122 in run
  File "/var/lib/buildbot/workers/rise-riscv64-4/3.15.rise-riscv64-4/build/Lib/unittest/suite.py", line 84 in __call__
  File "/var/lib/buildbot/workers/rise-riscv64-4/3.15.rise-riscv64-4/build/Lib/unittest/suite.py", line 122 in run
  File "/var/lib/buildbot/workers/rise-riscv64-4/3.15.rise-riscv64-4/build/Lib/unittest/suite.py", line 84 in __call__
  File "/var/lib/buildbot/workers/rise-riscv64-4/3.15.rise-riscv64-4/build/Lib/unittest/runner.py", line 256 in run
  File "/var/lib/buildbot/workers/rise-riscv64-4/3.15.rise-riscv64-4/build/Lib/test/libregrtest/single.py", line 84 in _run_suite
  File "/var/lib/buildbot/workers/rise-riscv64-4/3.15.rise-riscv64-4/build/Lib/test/libregrtest/single.py", line 42 in run_unittest
  File "/var/lib/buildbot/workers/rise-riscv64-4/3.15.rise-riscv64-4/build/Lib/test/libregrtest/single.py", line 162 in test_func
  File "/var/lib/buildbot/workers/rise-riscv64-4/3.15.rise-riscv64-4/build/Lib/test/libregrtest/single.py", line 118 in regrtest_runner
  File "/var/lib/buildbot/workers/rise-riscv64-4/3.15.rise-riscv64-4/build/Lib/test/libregrtest/single.py", line 165 in _load_run_test
  File "/var/lib/buildbot/workers/rise-riscv64-4/3.15.rise-riscv64-4/build/Lib/test/libregrtest/single.py", line 210 in _runtest_env_changed_exc
  File "/var/lib/buildbot/workers/rise-riscv64-4/3.15.rise-riscv64-4/build/Lib/test/libregrtest/single.py", line 319 in _runtest
  File "/var/lib/buildbot/workers/rise-riscv64-4/3.15.rise-riscv64-4/build/Lib/test/libregrtest/single.py", line 348 in run_single_test
  File "/var/lib/buildbot/workers/rise-riscv64-4/3.15.rise-riscv64-4/build/Lib/test/libregrtest/worker.py", line 99 in worker_process
  File "/var/lib/buildbot/workers/rise-riscv64-4/3.15.rise-riscv64-4/build/Lib/test/libregrtest/worker.py", line 137 in main
  File "/var/lib/buildbot/workers/rise-riscv64-4/3.15.rise-riscv64-4/build/Lib/test/libregrtest/worker.py", line 141 in <module>
  File "/var/lib/buildbot/workers/rise-riscv64-4/3.15.rise-riscv64-4/build/Lib/runpy.py", line 87 in _run_code
  File "/var/lib/buildbot/workers/rise-riscv64-4/3.15.rise-riscv64-4/build/Lib/runpy.py", line 201 in _run_module_as_main