[Twisted-Python] process changes causing buildbot failures on win7?

[Glyph Lefkowitz]

These failures:

===============================================================================
[FAIL]
Traceback (most recent call last):
  File "C:\Users\Build Slave\bot-glyph-6\windows7-64-py2.7-select\Twisted\twisted\internet\test\test_process.py", line 361, in test_systemCallUninterruptedByChildExit
    self.assertEqual(result, ["Foo\n"])
  File "C:\Users\Build Slave\bot-glyph-6\windows7-64-py2.7-select\Twisted\twisted\trial\_synctest.py", line 437, in assertEqual
    super(_Assertions, self).assertEqual(first, second, msg)
  File "C:\Python27\Lib\unittest\case.py", line 513, in assertEqual
    assertion_func(first, second, msg=msg)
  File "C:\Python27\Lib\unittest\case.py", line 742, in assertListEqual
    self.assertSequenceEqual(list1, list2, msg, seq_type=list)
  File "C:\Python27\Lib\unittest\case.py", line 724, in assertSequenceEqual
    self.fail(msg)
twisted.trial.unittest.FailTest: Lists differ: [''] != ['Foo\n']

First differing element 0:

Foo


- ['']
+ ['Foo\n']

twisted.internet.test.test_process.ProcessTestsBuilder_IOCPReactorTests.test_systemCallUninterruptedByChildExit
twisted.internet.test.test_process.ProcessTestsBuilder_SelectReactorTests.test_systemCallUninterruptedByChildExit
twisted.internet.test.test_process.ProcessTestsBuilder_Win32ReactorTests.test_systemCallUninterruptedByChildExit

have started happening on the buildbot on trunk: https://buildbot.twistedmatrix.com/builders/windows7-64-py2.7/builds/5215/steps/select/logs/problems

soon after this change: http://twistedmatrix.com/trac/changeset/45725

Unfortunately the buildbot was in a kind of unrelated bad state when it landed, and the configuration is a bit different now, so I'm not sure if this is a regression or a configuration error.  But given that the change was about processes, and the failure is in the process test, I thought it might bear some investigation...

-glyph
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