TST: fix cumcount test on 32-bit env

[gdraps]

Fix test_groupby.test_cumcount_empty() on 32-bit platforms by specifying expected dtype of 'int64'.

====================================================================== FAIL: test_cumcount_empty (pandas.tests.test_groupby.TestGroupBy) ---------------------------------------------------------------------- Traceback (most recent call last): File "/home/gmd/github_shadow/pandas/pandas/tests/test_groupby.py", line 2579, in test_cumcount_empty assert_series_equal(e, ge.cumcount()) File "/home/gmd/github_shadow/pandas/pandas/util/testing.py", line 423, in assert_series_equal assert_attr_equal('dtype', left, right) File "/home/gmd/github_shadow/pandas/pandas/util/testing.py", line 407, in assert_attr_equal assert_equal(left_attr,right_attr,"attr is not equal [{0}]" .format(attr)) File "/home/gmd/github_shadow/pandas/pandas/util/testing.py", line 390, in assert_equal assert a == b, "%s: %r != %r" % (msg.format(a,b), a, b) AssertionError: attr is not equal [dtype]: dtype('int32') != dtype('int64') 

[jtratner]

We should add a note about using int64 instead of int. Not that it will
necessarily resolve this completely.

[jtratner]

Thanks for catching this! I'm hoping we can get an automatic 32bit build from Travis at some point.

[gdraps]

Thanks Jeff.. For completeness, here's the open issue tracking 32-bit env support in Travis: travis-ci/travis-ci#986