python-tornado FTBFS with this proposed-pocket.

see e.g. the good build
https://launchpadlibrarian.net/421462446/buildlog_ubuntu-bionic-ppc64el.python-tornado_4.5.3-1build1_BUILDING.txt.gz
(release only pocket)
and the bad one:
https://launchpadlibrarian.net/421443840/buildlog_ubuntu-bionic-amd64.python-tornado_4.5.3-1build1_BUILDING.txt.gz
(proposed pocket)

test_inline_read_error (tornado.test.iostream_test.TestIOStreamSSL) ... FAIL
test_read_until_close_after_close (tornado.test.iostream_test.TestIOStreamSSL) ... FAIL
test_streaming_read_until_close_after_close (tornado.test.iostream_test.TestIOStreamSSL) ... FAIL
test_write_zero_bytes (tornado.test.iostream_test.TestIOStreamSSL) ... FAIL
test_inline_read_error (tornado.test.iostream_test.TestIOStreamSSLContext) ... FAIL
test_read_until_close_after_close (tornado.test.iostream_test.TestIOStreamSSLContext) ... FAIL
test_streaming_read_until_close_after_close (tornado.test.iostream_test.TestIOStreamSSLContext) ... FAIL
test_write_zero_bytes (tornado.test.iostream_test.TestIOStreamSSLContext) ... FAIL


======================================================================
FAIL: test_inline_read_error (tornado.test.iostream_test.TestIOStreamSSL)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/<<PKGBUILDDIR>>/tornado/testing.py", line 136, in __call__
    result = self.orig_method(*args, **kwargs)
  File "/<<PKGBUILDDIR>>/tornado/test/iostream_test.py", line 556, in test_inline_read_error
    server.read_bytes(1, lambda data: None)
AssertionError: error not raised

======================================================================
FAIL: test_read_until_close_after_close (tornado.test.iostream_test.TestIOStreamSSL)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/<<PKGBUILDDIR>>/tornado/testing.py", line 136, in __call__
    result = self.orig_method(*args, **kwargs)
  File "/<<PKGBUILDDIR>>/tornado/test/iostream_test.py", line 451, in test_read_until_close_after_close
    data = self.wait()
  File "/<<PKGBUILDDIR>>/tornado/testing.py", line 336, in wait
    self.__rethrow()
  File "/<<PKGBUILDDIR>>/tornado/testing.py", line 272, in __rethrow
    raise_exc_info(failure)
  File "/<<PKGBUILDDIR>>/tornado/testing.py", line 320, in timeout_func
    timeout)
AssertionError: Async operation timed out after 5 seconds

======================================================================
FAIL: test_streaming_read_until_close_after_close (tornado.test.iostream_test.TestIOStreamSSL)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/<<PKGBUILDDIR>>/tornado/testing.py", line 136, in __call__
    result = self.orig_method(*args, **kwargs)
  File "/<<PKGBUILDDIR>>/tornado/test/iostream_test.py", line 481, in test_streaming_read_until_close_after_close
    data = self.wait()
  File "/<<PKGBUILDDIR>>/tornado/testing.py", line 336, in wait
    self.__rethrow()
  File "/<<PKGBUILDDIR>>/tornado/testing.py", line 272, in __rethrow
    raise_exc_info(failure)
  File "/<<PKGBUILDDIR>>/tornado/testing.py", line 320, in timeout_func
    timeout)
AssertionError: Async operation timed out after 5 seconds

======================================================================
FAIL: test_write_zero_bytes (tornado.test.iostream_test.TestIOStreamSSL)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/<<PKGBUILDDIR>>/tornado/testing.py", line 136, in __call__
    result = self.orig_method(*args, **kwargs)
  File "/<<PKGBUILDDIR>>/tornado/test/iostream_test.py", line 220, in test_write_zero_bytes
    self.wait()
  File "/<<PKGBUILDDIR>>/tornado/testing.py", line 336, in wait
    self.__rethrow()
  File "/<<PKGBUILDDIR>>/tornado/testing.py", line 272, in __rethrow
    raise_exc_info(failure)
  File "/<<PKGBUILDDIR>>/tornado/testing.py", line 320, in timeout_func
    timeout)
AssertionError: Async operation timed out after 5 seconds

======================================================================
FAIL: test_inline_read_error (tornado.test.iostream_test.TestIOStreamSSLContext)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/<<PKGBUILDDIR>>/tornado/testing.py", line 136, in __call__
    result = self.orig_method(*args, **kwargs)
  File "/<<PKGBUILDDIR>>/tornado/test/iostream_test.py", line 556, in test_inline_read_error
    server.read_bytes(1, lambda data: None)
AssertionError: error not raised

======================================================================
FAIL: test_read_until_close_after_close (tornado.test.iostream_test.TestIOStreamSSLContext)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/<<PKGBUILDDIR>>/tornado/testing.py", line 136, in __call__
    result = self.orig_method(*args, **kwargs)
  File "/<<PKGBUILDDIR>>/tornado/test/iostream_test.py", line 451, in test_read_until_close_after_close
    data = self.wait()
  File "/<<PKGBUILDDIR>>/tornado/testing.py", line 336, in wait
    self.__rethrow()
  File "/<<PKGBUILDDIR>>/tornado/testing.py", line 272, in __rethrow
    raise_exc_info(failure)
  File "/<<PKGBUILDDIR>>/tornado/testing.py", line 320, in timeout_func
    timeout)
AssertionError: Async operation timed out after 5 seconds

======================================================================
FAIL: test_streaming_read_until_close_after_close (tornado.test.iostream_test.TestIOStreamSSLContext)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/<<PKGBUILDDIR>>/tornado/testing.py", line 136, in __call__
    result = self.orig_method(*args, **kwargs)
  File "/<<PKGBUILDDIR>>/tornado/test/iostream_test.py", line 481, in test_streaming_read_until_close_after_close
    data = self.wait()
  File "/<<PKGBUILDDIR>>/tornado/testing.py", line 336, in wait
    self.__rethrow()
  File "/<<PKGBUILDDIR>>/tornado/testing.py", line 272, in __rethrow
    raise_exc_info(failure)
  File "/<<PKGBUILDDIR>>/tornado/testing.py", line 320, in timeout_func
    timeout)
AssertionError: Async operation timed out after 5 seconds

======================================================================
FAIL: test_write_zero_bytes (tornado.test.iostream_test.TestIOStreamSSLContext)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/<<PKGBUILDDIR>>/tornado/testing.py", line 136, in __call__
    result = self.orig_method(*args, **kwargs)
  File "/<<PKGBUILDDIR>>/tornado/test/iostream_test.py", line 220, in test_write_zero_bytes
    self.wait()
  File "/<<PKGBUILDDIR>>/tornado/testing.py", line 336, in wait
    self.__rethrow()
  File "/<<PKGBUILDDIR>>/tornado/testing.py", line 272, in __rethrow
    raise_exc_info(failure)
  File "/<<PKGBUILDDIR>>/tornado/testing.py", line 320, in timeout_func
    timeout)
AssertionError: Async operation timed out after 5 seconds