test_to_hdf_with_object_column_names and test_to_csv_defualt_encoding weird failures
While trying to build Debian package of 0.22 I am running into two  strange test failures:
### 1
```
self = <pandas.tests.io.test_pytables.TestHDFStore object at 0x7ff583fbe110>

    def test_to_hdf_with_object_column_names(self):
        # GH9057
        # Writing HDF5 table format should only work for string-like
        # column types
    
        types_should_fail = [tm.makeIntIndex, tm.makeFloatIndex,
                             tm.makeDateIndex, tm.makeTimedeltaIndex,
                             tm.makePeriodIndex]
        types_should_run = [tm.makeStringIndex, tm.makeCategoricalIndex]
    
        if compat.PY3:
            types_should_run.append(tm.makeUnicodeIndex)
        else:
            types_should_fail.append(tm.makeUnicodeIndex)
    
        for index in types_should_fail:
            df = DataFrame(np.random.randn(10, 2), columns=index(2))
            with ensure_clean_path(self.path) as path:
                with catch_warnings(record=True):
                    with pytest.raises(
                        ValueError, msg=("cannot have non-object label "
                                         "DataIndexableCol")):
                        df.to_hdf(path, 'df', format='table',
>                                 data_columns=True)

../debian/tmp/usr/lib/python2.7/dist-packages/pandas/tests/io/test_pytables.py:5035: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
../debian/tmp/usr/lib/python2.7/dist-packages/pandas/core/generic.py:1471: in to_hdf
    return pytables.to_hdf(path_or_buf, key, self, **kwargs)
../debian/tmp/usr/lib/python2.7/dist-packages/pandas/io/pytables.py:281: in to_hdf
    f(store)
../debian/tmp/usr/lib/python2.7/dist-packages/pandas/io/pytables.py:275: in <lambda>
    f = lambda store: store.put(key, value, **kwargs)
../debian/tmp/usr/lib/python2.7/dist-packages/pandas/io/pytables.py:866: in put
    self._write_to_group(key, value, append=append, **kwargs)
../debian/tmp/usr/lib/python2.7/dist-packages/pandas/io/pytables.py:1341: in _write_to_group
    s.write(obj=value, append=append, complib=complib, **kwargs)
../debian/tmp/usr/lib/python2.7/dist-packages/pandas/io/pytables.py:3924: in write
    self._handle.create_table(self.group, **options)
/usr/lib/python2.7/dist-packages/tables/file.py:1055: in create_table
    chunkshape=chunkshape, byteorder=byteorder)
/usr/lib/python2.7/dist-packages/tables/table.py:833: in __init__
    byteorder, _log)
/usr/lib/python2.7/dist-packages/tables/leaf.py:272: in __init__
    super(Leaf, self).__init__(parentnode, name, _log)
/usr/lib/python2.7/dist-packages/tables/node.py:266: in __init__
    self._v_objectid = self._g_create()
/usr/lib/python2.7/dist-packages/tables/table.py:1020: in _g_create
    self._v_new_title, self.filters.complib or '', obversion)
tables/tableextension.pyx:181: in tables.tableextension.Table._create_table
    ???
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 

>   ???
E   KeyError: "Field named '\\u05d8\\u05e70\\u05e3\\u05d1\\u05dc\\u05dd\\u05e1\\u05dd7' not found."
```
FWIW :
```
(Pdb) print u'\u05d8\u05e70\u05e3\u05d1\u05dc\u05dd\u05e1\u05dd7'
טק0ףבלםסם7
```
This, and another test (pandas/tests/io/formats/test_to_csv.py::TestToCSV::test_to_csv_defualt_encoding) seems to pass if I run only them, without all the rest ... so smells like there could be some cross-tests dependency/shared state (that is my day today to figure out such tests, also in our datalad, heh):

## 2
```
../debian/tmp/usr/lib/python2.7/dist-packages/pandas/tests/io/formats/test_to_csv.py::TestToCSV::test_to_csv_defualt_encoding FAILED
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> traceback >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

self = <pandas.tests.io.formats.test_to_csv.TestToCSV object at 0x7ff58467a6d0>

    def test_to_csv_defualt_encoding(self):
        # GH17097
        df = DataFrame({'col': [u"AAAAA", u"ÄÄÄÄÄ", u"ßßßßß", u"聞聞聞聞聞"]})
    
        with tm.ensure_clean('test.csv') as path:
            # the default to_csv encoding in Python 2 is ascii, and that in
            # Python 3 is uft-8.
            if pd.compat.PY2:
                # the encoding argument parameter should be utf-8
                with tm.assert_raises_regex(UnicodeEncodeError, 'ascii'):
>                   df.to_csv(path)

../debian/tmp/usr/lib/python2.7/dist-packages/pandas/tests/io/formats/test_to_csv.py:21: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 

self = <pandas.util.testing._AssertRaisesContextmanager object at 0x7ff58467a1d0>, exc_type = None, exc_value = None, trace_back = None

    def __exit__(self, exc_type, exc_value, trace_back):
        expected = self.exception
    
        if not exc_type:
            exp_name = getattr(expected, "__name__", str(expected))
>           raise AssertionError("{name} not raised.".format(name=exp_name))
E           AssertionError: UnicodeEncodeError not raised.

../debian/tmp/usr/lib/python2.7/dist-packages/pandas/util/testing.py:2500: AssertionError
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> entering PDB >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> /home/yoh/deb/gits/pkg-exppsy/pandas/debian/tmp/usr/lib/python2.7/dist-packages/pandas/util/testing.py(2500)__exit__()
-> raise AssertionError("{name} not raised.".format(name=exp_name))
```
ok -- I tripple checked now that they pass if I just run them.  Here is my sample invocation
```
export PYTHONPATH=`/bin/ls -d $PWD/debian/tmp/usr/lib/python$PY/*/`; \
export MPLCONFIGDIR=/home/yoh/deb/gits/pkg-exppsy/pandas/build HOME=/home/yoh/deb/gits/pkg-exppsy/pandas/build; \
python2.7 ci/print_versions.py; \
    cd build/; LOCALE_OVERRIDE=C xvfb-run -a -s "-screen 0 1280x1024x24 -noreset" \
      python2.7 -m pytest -s -v -m 'not single and not network and not disabled'   -m "not intel" --pdb $PYTHONPATH/pandas/tests/io/formats/test_to_csv.py::TestToCSV::test_to_csv_defualt_encoding $PYTHONPATH/pandas/tests/io/test_pytables.py::TestHDFStore::test_to_hdf_with_object_column_names;
```
and it is `$PYTHONPATH/pandas` when I want to run them all.

I wondered if anyone observed something like that before or has a clue on what could cause such behavior?