Python 3.8b1 miscompiles conditional expressions containing __debug__

[mgedmin]

BPO	37269
Nosy	@mgedmin, @pablogsal, @miss-islington
PRs	bpo-37269: Correctly optimize constant conditionals of binops #14071 [3.8] bpo-37269: Correctly optimise conditionals with constant booleans (GH-14071) #14072 [3.7] bpo-37269: Correctly optimise conditionals with constant booleans (GH-14071) #14073

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = None
closed_at = <Date 2019-06-14.06:19:13.942>
created_at = <Date 2019-06-13.18:56:04.786>
labels = ['interpreter-core', '3.8', '3.9']
title = 'Python 3.8b1 miscompiles conditional expressions containing __debug__'
updated_at = <Date 2019-06-14.06:19:13.941>
user = 'https://github.com/mgedmin'

bugs.python.org fields:

activity = <Date 2019-06-14.06:19:13.941>
actor = 'pablogsal'
assignee = 'none'
closed = True
closed_date = <Date 2019-06-14.06:19:13.942>
closer = 'pablogsal'
components = ['Interpreter Core']
creation = <Date 2019-06-13.18:56:04.786>
creator = 'mgedmin'
dependencies = []
files = []
hgrepos = []
issue_num = 37269
keywords = ['patch']
message_count = 5.0
messages = ['345533', '345552', '345554', '345555', '345556']
nosy_count = 3.0
nosy_names = ['mgedmin', 'pablogsal', 'miss-islington']
pr_nums = ['14071', '14072', '14073']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = None
url = 'https://bugs.python.org/issue37269'
versions = ['Python 3.8', 'Python 3.9']

[mgedmin]

Python 3.8 miscompiles the following code:

    $ cat /tmp/wat.py
    enable_debug = False

    if not enable_debug or not __debug__:
        print("you shall not pass!")

    $ python3.7 /tmp/wat.py
    you shall not pass!

    $ python3.8 /tmp/wat.py

(no output is produced.)

This is a distilled example from zope.traversing's codebase (zopefoundation/zope.traversing#13).

[pablogsal]

New changeset 05f8318 by Pablo Galindo in branch 'master':
bpo-37269: Correctly optimise conditionals with constant booleans (GH-14071)
05f8318

[miss-islington]

New changeset 7cd581a by Miss Islington (bot) in branch '3.8':
bpo-37269: Correctly optimise conditionals with constant booleans (GH-14071)
7cd581a

[pablogsal]

New changeset 5292179 by Pablo Galindo in branch '3.7':
[3.7] bpo-37269: Correctly optimise conditionals with constant booleans (GH-14071) (GH-14073)
5292179

[pablogsal]

Thanks, Marius for the report!