IDLE: in shell, time.sleep ignores _thread.interrupt_main()

GitHub fields:

assignee = 'https://github.com/terryjreedy'
closed_at = None
created_at = <Date 2017-03-27.22:51:11.745>
labels = ['expert-IDLE', 'type-bug', '3.9']
title = 'IDLE: in shell, time.sleep ignores _thread.interrupt_main()'
updated_at = <Date 2019-09-19.18:42:59.551>
user = 'https://bugs.python.org/Mark'

bugs.python.org fields:

activity = <Date 2019-09-19.18:42:59.551>
actor = 'terry.reedy'
assignee = 'terry.reedy'
closed = False
closed_date = None
closer = None
components = ['IDLE']
creation = <Date 2017-03-27.22:51:11.745>
creator = 'Mark'
dependencies = []
files = ['46771']
hgrepos = []
issue_num = 29926
keywords = ['patch']
message_count = 31.0
messages = ['290663', '290675', '290677', '290679', '290715', '290728', '290743', '290744', '290749', '290751', '290761', '291049', '291052', '291054', '297157', '297163', '297176', '297241', '297242', '297286', '297288', '297291', '297307', '297323', '297330', '297334', '297345', '297347', '297349', '297352', '297477']
nosy_count = 7.0
nosy_names = ['terry.reedy', 'pitrou', 'njs', 'martin.panter', 'Mark', 'eryksun', 'louielu']
pr_nums = ['2466']
priority = 'normal'
resolution = None
stage = 'needs patch'
status = 'open'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue29926'
versions = ['Python 3.9']