> Have no ideas why tests are failed and only on this buildbot.

test_codecs always crash on Python 3.6 with Python compiled in debug mode:

test_errors (test.test_codecs.UTF7Test) ... python: Objects/unicodeobject.c:1263: _copy_characters: Assertion `ch <= to_maxchar' failed.
Fatal Python error: Aborted

Current thread 0x00007f1489057700 (most recent call first):
  File "/home/haypo/prog/python/default/Lib/encodings/utf_7.py", line 12 in decode
  File "/home/haypo/prog/python/default/Lib/test/test_codecs.py", line 1021 in test_errors
  File "/home/haypo/prog/python/default/Lib/unittest/case.py", line 600 in run
  File "/home/haypo/prog/python/default/Lib/unittest/case.py", line 648 in __call__
  File "/home/haypo/prog/python/default/Lib/unittest/suite.py", line 122 in run
  File "/home/haypo/prog/python/default/Lib/unittest/suite.py", line 84 in __call__
  File "/home/haypo/prog/python/default/Lib/unittest/suite.py", line 122 in run
  File "/home/haypo/prog/python/default/Lib/unittest/suite.py", line 84 in __call__
  File "/home/haypo/prog/python/default/Lib/unittest/suite.py", line 122 in run
  File "/home/haypo/prog/python/default/Lib/unittest/suite.py", line 84 in __call__
  File "/home/haypo/prog/python/default/Lib/unittest/runner.py", line 176 in run
  File "/home/haypo/prog/python/default/Lib/test/support/__init__.py", line 1775 in _run_suite
  File "/home/haypo/prog/python/default/Lib/test/support/__init__.py", line 1809 in run_unittest
  File "/home/haypo/prog/python/default/Lib/test/libregrtest/runtest.py", line 159 in test_runner
  File "/home/haypo/prog/python/default/Lib/test/libregrtest/runtest.py", line 160 in runtest_inner
  File "/home/haypo/prog/python/default/Lib/test/libregrtest/runtest.py", line 124 in runtest
  File "/home/haypo/prog/python/default/Lib/test/libregrtest/main.py", line 285 in run_tests_sequential
  File "/home/haypo/prog/python/default/Lib/test/libregrtest/main.py", line 344 in run_tests
  File "/home/haypo/prog/python/default/Lib/test/libregrtest/main.py", line 380 in main
  File "/home/haypo/prog/python/default/Lib/test/libregrtest/main.py", line 421 in main
  File "/home/haypo/prog/python/default/Lib/test/libregrtest/main.py", line 443 in main_in_temp_cwd
  File "/home/haypo/prog/python/default/Lib/test/__main__.py", line 3 in <module>
  File "/home/haypo/prog/python/default/Lib/runpy.py", line 85 in _run_code
  File "/home/haypo/prog/python/default/Lib/runpy.py", line 170 in _run_module_as_main
Abandon (core dumped)