Unicode re split issues

split.py

$ python
Python 3.6.8 (default, Dec 20 2019, 11:17:32) 
[GCC 5.4.0 20160609] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> a='İrəli'
>>> len(a)
5
>>> len(a.lower())
6
>>> import re
>>> re.split('\\W', a)
['İrəli']
>>> re.split('\\W', a.lower())
['i', 'rəli']
>>> [len(x) for x in re.split('\\W', a.lower())]
[1, 4]
>>> sum(len(x.lower()) for x in a)
6
>>> len(a.lower())
6
>>> list(a)
['İ', 'r', 'ə', 'l', 'i']
>>> list(a.lower())
['i', '̇', 'r', 'ə', 'l', 'i']
>>> [x.isalpha() for x in a.lower()]
[True, False, True, True, True, True]

>>> [ascii(x.lower()) for x in 'İ']
["'i\\u0307'"]
>>> [ascii(x) for x in 'İ'.lower()]
["'i'", "'\\u0307'"]