Slice confusing with negative stop and strides and the 0th element.

GitHub fields:

assignee = None
closed_at = None
created_at = <Date 2016-12-06.05:06:40.291>
labels = ['3.7', 'docs']
title = 'Slice confusing with negative stop and strides and the 0th element.'
updated_at = <Date 2016-12-10.00:28:35.180>
user = 'https://github.com/hardkrash'

bugs.python.org fields:

activity = <Date 2016-12-10.00:28:35.180>
actor = 'martin.panter'
assignee = 'docs@python'
closed = False
closed_date = None
closer = None
components = ['Documentation']
creation = <Date 2016-12-06.05:06:40.291>
creator = 'hardkrash'
dependencies = []
files = []
hgrepos = []
issue_num = 28882
keywords = []
message_count = 6.0
messages = ['282500', '282501', '282578', '282801', '282810', '282814']
nosy_count = 5.0
nosy_names = ['terry.reedy', 'hardkrash', 'docs@python', 'martin.panter', 'josh.r']
pr_nums = []
priority = 'normal'
resolution = None
stage = 'needs patch'
status = 'open'
superseder = None
type = None
url = 'https://bugs.python.org/issue28882'
versions = ['Python 3.5', 'Python 3.6', 'Python 3.7']