Issue 1:
Code Sample, a copy-pastable example if possible

import pandas as pd
data = [{'id': 1, 'buyer': 'A'}, {'id': 2, 'buyer': 'B'}]
df = pd.DataFrame(data, index=pd.date_range('2016-01-01', periods=2))
resampler = df.groupby('id').resample('1D')

If I then run resampler['buyer'].count() first time, it will output normally:

id
1 2016-01-01 1
2 2016-01-02 1
Name: buyer, dtype: int64

If I then run resampler['buyer'].count() again, it will report error:

/usr/local/bin/ipython:1: FutureWarning: .resample() is now a deferred operation
use .resample(...).mean() instead of .resample(...)
#!/usr/local/opt/python/bin/python2.7
---------------------------------------------------------------------------
KeyError Traceback (most recent call last)
<ipython-input-30-5714547cf98c> in <module>()
----> 1 resampler['buyer'].count()

/usr/local/lib/python2.7/site-packages/pandas/tseries/resample.pyc in __getitem__(self, key)
179 # compat for deprecated
180 if isinstance(self.obj, com.ABCSeries):
--> 181 return self._deprecated()[key]
182
183 raise

/usr/local/lib/python2.7/site-packages/pandas/core/frame.pyc in __getitem__(self, key)
1995 return self._getitem_multilevel(key)
1996 else:
-> 1997 return self._getitem_column(key)
1998
1999 def _getitem_column(self, key):

/usr/local/lib/python2.7/site-packages/pandas/core/frame.pyc in _getitem_column(self, key)
2002 # get column
2003 if self.columns.is_unique:
-> 2004 return self._get_item_cache(key)
2005
2006 # duplicate columns & possible reduce dimensionality

/usr/local/lib/python2.7/site-packages/pandas/core/generic.pyc in _get_item_cache(self, item)
1348 res = cache.get(item)
1349 if res is None:
-> 1350 values = self._data.get(item)
1351 res = self._box_item_values(item, values)
1352 cache[item] = res

/usr/local/lib/python2.7/site-packages/pandas/core/internals.pyc in get(self, item, fastpath)
3288
3289 if not isnull(item):
-> 3290 loc = self.items.get_loc(item)
3291 else:
3292 indexer = np.arange(len(self.items))[isnull(self.items)]

/usr/local/lib/python2.7/site-packages/pandas/indexes/base.pyc in get_loc(self, key, method, tolerance)
1945 return self._engine.get_loc(key)
1946 except KeyError:
-> 1947 return self._engine.get_loc(self._maybe_cast_indexer(key))
1948
1949 indexer = self.get_indexer([key], method=method, tolerance=tolerance)

pandas/index.pyx in pandas.index.IndexEngine.get_loc (pandas/index.c:4154)()

pandas/index.pyx in pandas.index.IndexEngine.get_loc (pandas/index.c:4018)()

pandas/hashtable.pyx in pandas.hashtable.PyObjectHashTable.get_item (pandas/hashtable.c:12368)()

pandas/hashtable.pyx in pandas.hashtable.PyObjectHashTable.get_item (pandas/hashtable.c:12322)()

KeyError: 'buyer'

If I run df.groupby('id').resample('1D')['buyer'].count() instead of resampler['buyer'].count(), the problem will not appear.

What's the problem?

output of pd.show_versions()

INSTALLED VERSIONS

commit: None

python: 2.7.11.final.0

python-bits: 64

OS: Darwin

OS-release: 15.4.0

machine: x86_64

processor: i386

byteorder: little

LC_ALL: None

LANG: zh_CN.UTF-8

pandas: 0.18.1

nose: None

pip: 8.1.1

setuptools: 19.4

Cython: None

numpy: 1.11.0

scipy: None

statsmodels: None

xarray: None

IPython: 4.2.0

sphinx: 1.3.5

patsy: None

dateutil: 2.5.3

pytz: 2016.4

blosc: None

bottleneck: None

tables: None

numexpr: None

matplotlib: None

openpyxl: None

xlrd: None

xlwt: None

xlsxwriter: None

lxml: None

bs4: 4.4.1

html5lib: None

httplib2: None

apiclient: None

sqlalchemy: 1.0.12

pymysql: None

psycopg2: None

jinja2: 2.8

boto: None

pandas_datareader: None

Issue 2:
Followup to #21109

We'll need to refactor scripts/announce.py to update the list of contributors on each build.

Then we can enable spellcheck in the Travis doc build.