The ARM Ubuntu 3.x buildbot often fails test_dbm:

http://www.python.org/dev/buildbot/all/builders/ARM%20Ubuntu%203.x/builds/364/steps/test/logs/stdio
http://www.python.org/dev/buildbot/all/builders/ARM%20Ubuntu%203.x/builds/367/steps/test/logs/stdio
http://www.python.org/dev/buildbot/all/builders/ARM%20Ubuntu%203.x/builds/368/steps/test/logs/stdio
http://www.python.org/dev/buildbot/all/builders/ARM%20Ubuntu%203.x/builds/372/steps/test/logs/stdio

    ======================================================================
    ERROR: test_anydbm_creation (test.test_dbm.TestCase-dbm.ndbm)
    ----------------------------------------------------------------------
    Traceback (most recent call last):
      File "/var/lib/buildbot/buildarea/3.x.warsaw-ubuntu-arm/build/Lib/test/test_dbm.py", line 70, in test_anydbm_creation
        self.read_helper(f)
      File "/var/lib/buildbot/buildarea/3.x.warsaw-ubuntu-arm/build/Lib/test/test_dbm.py", line 111, in read_helper
        self.assertEqual(self._dict[key], f[key.encode("ascii")])
    KeyError: b'0'

    ======================================================================
    ERROR: test_anydbm_modification (test.test_dbm.TestCase-dbm.ndbm)
    ----------------------------------------------------------------------
    Traceback (most recent call last):
      File "/var/lib/buildbot/buildarea/3.x.warsaw-ubuntu-arm/build/Lib/test/test_dbm.py", line 85, in test_anydbm_modification
        self.read_helper(f)
      File "/var/lib/buildbot/buildarea/3.x.warsaw-ubuntu-arm/build/Lib/test/test_dbm.py", line 111, in read_helper
        self.assertEqual(self._dict[key], f[key.encode("ascii")])
    KeyError: b'0'

    ======================================================================
    ERROR: test_anydbm_read (test.test_dbm.TestCase-dbm.ndbm)
    ----------------------------------------------------------------------
    Traceback (most recent call last):
      File "/var/lib/buildbot/buildarea/3.x.warsaw-ubuntu-arm/build/Lib/test/test_dbm.py", line 91, in test_anydbm_read
        self.read_helper(f)
      File "/var/lib/buildbot/buildarea/3.x.warsaw-ubuntu-arm/build/Lib/test/test_dbm.py", line 111, in read_helper
        self.assertEqual(self._dict[key], f[key.encode("ascii")])
    KeyError: b'0'

The stdio logs also show possibly-related output on stderr:

    test test_dbm failed
    @test_27319_tmp.db: unable to flush: No such file or directory
    @test_27319_tmp.db: unable to flush: No such file or directory

This is printed before the error tracebacks, but I assume it actually
happens afterwards (which is entirely possible if stderr is line-buffered
and stdout is not).