IDLE should restart instead of hanging when subprocess exits

GitHub fields:

assignee = 'https://github.com/terryjreedy'
closed_at = None
created_at = <Date 2019-11-05.07:39:37.434>
labels = ['expert-IDLE', 'type-bug']
title = 'IDLE should restart instead of hanging when subprocess exits'
updated_at = <Date 2019-11-14.10:52:49.556>
user = 'https://github.com/terryjreedy'

bugs.python.org fields:

activity = <Date 2019-11-14.10:52:49.556>
actor = 'taleinat'
assignee = 'terry.reedy'
closed = False
closed_date = None
closer = None
components = ['IDLE']
creation = <Date 2019-11-05.07:39:37.434>
creator = 'terry.reedy'
dependencies = []
files = []
hgrepos = []
issue_num = 38695
keywords = ['patch']
message_count = 1.0
messages = ['356009']
nosy_count = 1.0
nosy_names = ['terry.reedy']
pr_nums = ['17152']
priority = 'normal'
resolution = None
stage = 'patch review'
status = 'open'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue38695'
versions = []