multiprocessing.Condition.notify_all() blocks indefinitely if a process waiting on it has died

GitHub fields:

assignee = None
closed_at = None
created_at = <Date 2017-07-20.11:29:48.884>
labels = ['type-bug', '3.7', 'OS-windows']
title = 'multiprocessing.Condition.notify_all() blocks indefinitely if a process waiting on it has died'
updated_at = <Date 2017-07-20.14:20:00.088>
user = 'https://github.com/mickp'

bugs.python.org fields:

activity = <Date 2017-07-20.14:20:00.088>
actor = 'pitrou'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Windows']
creation = <Date 2017-07-20.11:29:48.884>
creator = 'mickp'
dependencies = []
files = ['47025', '47027']
hgrepos = []
issue_num = 30975
keywords = []
message_count = 4.0
messages = ['298713', '298719', '298720', '298722']
nosy_count = 8.0
nosy_names = ['paul.moore', 'pitrou', 'tim.golden', 'sbt', 'zach.ware', 'steve.dower', 'davin', 'mickp']
pr_nums = []
priority = 'normal'
resolution = None
stage = 'needs patch'
status = 'open'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue30975'
versions = ['Python 2.7', 'Python 3.5', 'Python 3.6', 'Python 3.7']