See the following test (in Python 3.5):

>>> u'a\nb£'.encode('utf-8').splitlines()
['a', 'b\xc2\xa3']

I encode a string in UTF-8, then use the (bytes) splitlines function on it. The return value is a list of strings, containing encoded byte values.

The bytes object isn't even documented as having a splitlines method - and if it does, then it should be returning a list of bytes objects.

No, I have checked, it returns list of `bytes` objects.

$ python3.5
Python 3.5.0+ (default, Oct 11 2015, 09:05:38) 
[GCC 5.2.1 20151010] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> u'a\nb£'.encode('utf-8').splitlines()
[b'a', b'b\xc2\xa3']

works for me too on Windows:

Python 3.5.1 (v3.5.1:37a07cee5969, Dec  6 2015, 01:38:48) [MSC v.1900 32 bit (Intel)] on win32
Type "copyright", "credits" or "license()" for more information.
>>> u'a\nb£'.encode('utf-8').splitlines()
[b'a', b'b\xc2\xa3']

oh and documentation is here:
https://docs.python.org/3.5/library/stdtypes.html?highlight=bytes.splitlines#bytes.splitlines

Paul, I think you were in a Python 2 session:

$ python
Python 2.7.10 (v2.7.10:15c95b7d81dc, May 23 2015, 09:33:12) 
[GCC 4.2.1 (Apple Inc. build 5666) (dot 3)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> u'a\nb£'.encode('utf-8').splitlines()
['a', 'b\xc2\xa3']
>>> ^D
$ python3
Python 3.5.1 (v3.5.1:37a07cee5969, Dec  5 2015, 21:12:44) 
[GCC 4.2.1 (Apple Inc. build 5666) (dot 3)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> u'a\nb£'.encode('utf-8').splitlines()
[b'a', b'b\xc2\xa3']
>>>

That's weird. I can confirm it's working for me on 3.5.1. I'll double check I wan't in 2.7 when I'm back at my work PC, but I didn't *think* I was. But regardless, there's clearly no bug here.

Apologies for the confusion.

Sigh. I had installed Python 2.7 at some point, and py.exe picked it up by default :-(

Isn't it about time that py.exe defaulted to the latest version installed, not the latest version of Python 2?