allmydata.test.test_magic_folder.RealTestAliceBob.test_alice_bob sometimes fails on macOS with `Pending: set([u'file3'])`

[exarkun]

[FAIL]
Traceback (most recent call last):
Failure: testtools.testresult.real._StringException: twisted-log: 
2019-05-01 12:53:39-0700 [-] unable to set RLIMIT_NOFILE: current value (256, 9223372036854775807)
2019-05-01 12:53:39-0700 [-] unable to set RLIMIT_NOFILE: current value (256, 9223372036854775807)
2019-05-01 12:53:39-0700 [-] NevowSite starting on 50199
2019-05-01 12:53:39-0700 [-] Starting factory <nevow.appserver.NevowSite instance at 0x10c1c02d8>
2019-05-01 12:53:39-0700 [-] NevowSite starting on 50200
2019-05-01 12:53:39-0700 [-] Starting factory <nevow.appserver.NevowSite instance at 0x10f677248>
2019-05-01 12:53:39-0700 [-] Completed initial Magic Folder scan successfully (<allmydata.frontends.magic_folder.Downloader object at 0x10f22ec10>)
2019-05-01 12:53:39-0700 [-] Completed initial Magic Folder scan successfully (<allmydata.frontends.magic_folder.Downloader object at 0x10cbf9dd0>)
2019-05-01 12:53:43-0700 [-] (TCP Port 50200 Closed)
2019-05-01 12:53:43-0700 [-] Stopping factory <nevow.appserver.NevowSite instance at 0x10f677248>
2019-05-01 12:53:43-0700 [-] (TCP Port 50199 Closed)
2019-05-01 12:53:43-0700 [-] Stopping factory <nevow.appserver.NevowSite instance at 0x10c1c02d8>
2019-05-01 12:53:43-0700 [-] Main loop terminated.

Traceback (most recent call last):
  File "/private/var/lib/buildslave/bb-tahoe/OS-X_10_13/build/.tox/py27/lib/python2.7/site-packages/twisted/internet/defer.py", line 1418, in _inlineCallbacks
    result = g.send(result)
  File "/private/var/lib/buildslave/bb-tahoe/OS-X_10_13/build/.tox/py27/lib/python2.7/site-packages/eliot/_generators.py", line 139, in wrapper
    value_out = gen.send(value_in)
  File "/private/var/lib/buildslave/bb-tahoe/OS-X_10_13/build/src/allmydata/test/test_magic_folder.py", line 1727, in check_state
    self._check_uploader_count('objects_queued', 0, magic=self.bob_magicfolder)
  File "/private/var/lib/buildslave/bb-tahoe/OS-X_10_13/build/src/allmydata/test/test_magic_folder.py", line 766, in _check_uploader_count
    "Deque:   {}\n".format(magic.uploader._pending, magic.uploader._deque),
  File "/private/var/lib/buildslave/bb-tahoe/OS-X_10_13/build/src/allmydata/test/common_util.py", line 88, in failUnlessReallyEqual
    self.assertEqual(a, b, msg)
  File "/private/var/lib/buildslave/bb-tahoe/OS-X_10_13/build/.tox/py27/lib/python2.7/site-packages/testtools/testcase.py", line 411, in assertEqual
    self.assertThat(observed, matcher, message)
  File "/private/var/lib/buildslave/bb-tahoe/OS-X_10_13/build/.tox/py27/lib/python2.7/site-packages/testtools/testcase.py", line 498, in assertThat
    raise mismatch_error
testtools.matchers._impl.MismatchError: 1 != 0: Pending: set([u'file3'])
Deque:   deque([<allmydata.frontends.magic_folder.UploadItem object at 0x10db940d0>])


allmydata.test.test_magic_folder.RealTestAliceBob.test_alice_bob

[exarkun]

Saw it again, this time on TravisCI macOS:

[FAIL]
Traceback (most recent call last):
Failure: testtools.testresult.real._StringException: twisted-log: ---
2019-06-04 14:23:56+0000 [-] unable to set RLIMIT_NOFILE: current value (256, 9223372036854775807)
2019-06-04 14:23:56+0000 [-] unable to set RLIMIT_NOFILE: current value (256, 9223372036854775807)
2019-06-04 14:23:56+0000 [-] NevowSite starting on 54572
2019-06-04 14:23:56+0000 [-] Starting factory <nevow.appserver.NevowSite instance at 0x111f033f8>
2019-06-04 14:23:56+0000 [-] NevowSite starting on 54573
2019-06-04 14:23:56+0000 [-] Starting factory <nevow.appserver.NevowSite instance at 0x1127b46c8>
2019-06-04 14:23:56+0000 [-] Completed initial Magic Folder scan successfully (<allmydata.frontends.magic_folder.Downloader object at 0x113758210>)
2019-06-04 14:23:56+0000 [-] Completed initial Magic Folder scan successfully (<allmydata.frontends.magic_folder.Downloader object at 0x114bfbe90>)
2019-06-04 14:24:00+0000 [-] (TCP Port 54573 Closed)
2019-06-04 14:24:00+0000 [-] Stopping factory <nevow.appserver.NevowSite instance at 0x1127b46c8>
2019-06-04 14:24:00+0000 [-] (TCP Port 54572 Closed)
2019-06-04 14:24:00+0000 [-] Stopping factory <nevow.appserver.NevowSite instance at 0x111f033f8>
2019-06-04 14:24:00+0000 [-] Main loop terminated.
---
Traceback (most recent call last):
  File "/Users/travis/build/tahoe-lafs/tahoe-lafs/.tox/py27/lib/python2.7/site-packages/twisted/internet/defer.py", line 1418, in _inlineCallbacks
    result = g.send(result)
  File "/Users/travis/build/tahoe-lafs/tahoe-lafs/.tox/py27/lib/python2.7/site-packages/eliot/_generators.py", line 139, in wrapper
    value_out = gen.send(value_in)
  File "/Users/travis/build/tahoe-lafs/tahoe-lafs/.tox/py27/lib/python2.7/site-packages/allmydata/test/test_magic_folder.py", line 1727, in check_state
    self._check_uploader_count('objects_queued', 0, magic=self.bob_magicfolder)
  File "/Users/travis/build/tahoe-lafs/tahoe-lafs/.tox/py27/lib/python2.7/site-packages/allmydata/test/test_magic_folder.py", line 766, in _check_uploader_count
    "Deque:   {}\n".format(magic.uploader._pending, magic.uploader._deque),
  File "/Users/travis/build/tahoe-lafs/tahoe-lafs/.tox/py27/lib/python2.7/site-packages/allmydata/test/common_util.py", line 88, in failUnlessReallyEqual
    self.assertEqual(a, b, msg)
  File "/Users/travis/build/tahoe-lafs/tahoe-lafs/.tox/py27/lib/python2.7/site-packages/testtools/testcase.py", line 411, in assertEqual
    self.assertThat(observed, matcher, message)
  File "/Users/travis/build/tahoe-lafs/tahoe-lafs/.tox/py27/lib/python2.7/site-packages/testtools/testcase.py", line 498, in assertThat
    raise mismatch_error
testtools.matchers._impl.MismatchError: 1 != 0: Pending: set([u'file3'])
Deque:   deque([<allmydata.frontends.magic_folder.UploadItem object at 0x113e5ec90>])
allmydata.test.test_magic_folder.RealTestAliceBob.test_alice_bob