BUILD: build issues on windows

[jreback]

so from latest master w latest deps

• closed by BUG: DatetimeIndex raises AttributeError on win #13736

======================================================================
ERROR: test_nanosecond_field (pandas.tseries.tests.test_timeseries.TestDatetime64)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "C:\dev\pandas\pandas\tseries\tests\test_timeseries.py", line 3925, in test_nanosecond_field
    dti = DatetimeIndex(np.arange(10))
  File "C:\dev\pandas\pandas\util\decorators.py", line 91, in wrapper
    return func(*args, **kwargs)
  File "C:\dev\pandas\pandas\tseries\index.py", line 337, in __new__
    if isinstance(subarr, DatetimeIndex):
UnboundLocalError: local variable 'subarr' referenced before assignment

• closed by TST, COMPAT: Make MMapWrapper tests Windows compatible #13732

======================================================================
FAIL: test_next (pandas.io.tests.test_common.TestMMapWrapper)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "C:\dev\pandas\pandas\io\tests\test_common.py", line 141, in test_next
    self.assertEqual(next_line, line)
AssertionError: 'a,b,c\r\n' != 'a,b,c\n'
- a,b,c
?      -
+ a,b,c

I think some @sinhrks changes for the first
not sure about the 2nd, IIRC @pijucha saw this on windows as well

@gfyoung any idea?d

[sinhrks]

1st issue is caused by a test case uses np.int32 data (on windows). Will send a PR to fix the condition below.

• https://github.com/pydata/pandas/blob/master/pandas/tseries/index.py#L332

[gfyoung]

The second test is getting the content right, but it seems like an issue is what the newline is being read as at the end. For all intensive purposes, can add ".strip()" before the comparison .

[pijucha]

As for the second test:
On windows, I set up git to change newlines to \r\n in a working directory. So the file test_mmap.csv used in this test had \r\n. I noticed readlines() converted them to \n but MMapwrapper didn't.

[jreback]

closed by #13736 and #13732

[gfyoung]

@jreback : nit, check both boxes in the issue!