Hum, an assertion fails in set_reentrant(), helper function to set a TLS (Thread Local Storage), but I'm unable to reproduce the bug on my Fedora 23 (AMD64).

http://buildbot.python.org/all/builders/AMD64%20Debian%20root%203.x/builds/3316/steps/test/logs/stdio

[187/400] test_tracemalloc
python: ./Modules/_tracemalloc.c:174: set_reentrant: Assertion `PyThread_get_key_value(tracemalloc_reentrant_key) == ((PyObject *) &_Py_TrueStruct)' failed.
Fatal Python error: Aborted

Current thread 0x00007fecefd68700 (most recent call first):
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/test/test_tracemalloc.py", line 85 in setUp
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/unittest/case.py", line 596 in run
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/unittest/case.py", line 648 in __call__
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/unittest/suite.py", line 122 in run
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/unittest/suite.py", line 84 in __call__
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/unittest/suite.py", line 122 in run
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/unittest/suite.py", line 84 in __call__
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/unittest/runner.py", line 176 in run
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/test/support/__init__.py", line 1802 in _run_suite
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/test/support/__init__.py", line 1836 in run_unittest
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/test/test_tracemalloc.py", line 824 in test_main
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/test/libregrtest/runtest.py", line 162 in runtest_inner
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/test/libregrtest/runtest.py", line 115 in runtest
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/test/libregrtest/main.py", line 295 in run_tests_sequential
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/test/libregrtest/main.py", line 356 in run_tests
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/test/libregrtest/main.py", line 392 in main
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/test/libregrtest/main.py", line 433 in main
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/test/libregrtest/main.py", line 455 in main_in_temp_cwd
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/test/__main__.py", line 3 in <module>
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/runpy.py", line 85 in _run_code
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/runpy.py", line 184 in _run_module_as_main
Makefile:1026: recipe for target 'buildbottest' failed
make: *** [buildbottest] Aborted