Generator and coroutine repr could be more helpful

GitHub fields:

assignee = None
closed_at = None
created_at = <Date 2017-12-31.19:53:29.096>
labels = ['interpreter-core', 'type-feature', '3.8']
title = 'Generator and coroutine repr could be more helpful'
updated_at = <Date 2018-06-11.07:52:58.314>
user = 'https://github.com/pitrou'

bugs.python.org fields:

activity = <Date 2018-06-11.07:52:58.314>
actor = 'serhiy.storchaka'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Interpreter Core']
creation = <Date 2017-12-31.19:53:29.096>
creator = 'pitrou'
dependencies = []
files = []
hgrepos = []
issue_num = 32469
keywords = ['patch']
message_count = 3.0
messages = ['309302', '309315', '319280']
nosy_count = 5.0
nosy_names = ['pitrou', 'benjamin.peterson', 'serhiy.storchaka', 'yselivanov', 'tarasmatsyk']
pr_nums = ['5068']
priority = 'normal'
resolution = None
stage = 'patch review'
status = 'open'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue32469'
versions = ['Python 3.8']