Datetime field names use different normalization than calendar

[TomAugspurger]

At least under some conditions?

>>> import locale
>>> import calendar
>>> import unicodedata
>>> from pandas._libs.tslibs import fields
>>> locale_name = "crh_UA.UTF-8"
>>> x = fields.get_locale_names('f_month', locale_name)[6].capitalize()
>>> y = calendar.month_name[6].capitalize()

>>> x == y
# False

unicodedata.normalize("NFD", x) == unicodedata.normalize("NFD", y)
# True

this manifests in failures in #21814 (comment)

[TomAugspurger]

So two questions:

1. do we care enough to change this?
2. do we make an guarantees on what normalization we use, and if it matches python?

[TomAugspurger]

Once #21814 is in, this should be reproducible with

docker run -it --name=py36_locale continuumio/miniconda:latest /bin/bash 
git clone https://github.com/pandas-dev/pandas
cd pandas
sh ci/install_circle.sh