More specifically the cases that seem to have an issue
are when:
- the series in empty
- it's a single element series

Add a check so if the dtype is str is will create
an empty array type object and then pass the values.

Add test for an empty series. To chech that it fills the series
with NaN and not with 'n'.

Also add a test for cases that no string values are given.

To allow the developers to remember why the specific test was added

This is currently failing.

is_datetime64_dtype is trying to check the type
of unicodes but numpy does not support unicode and
this line breaks.

Add except error and return false
Test for unicode still fails for python 2

This was breaking for python 2.
The fix is to use pandas text_type to return string type

parametrize tests and use iloc to check value