zipimporter masks import errors

[AmundHov]

BPO	24792
Nosy	@Yhg1s, @gpshead, @ncoghlan, @ericsnowcurrently, @miss-islington, @iritkatriel
PRs	bpo-24792: Fix zipimporter masking the cause of import errors #22204

^{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 2020-12-20.17:06:37.498>
created_at = <Date 2015-08-05.08:51:02.859>
labels = ['type-bug', 'library', '3.10']
title = 'zipimporter masks import errors'
updated_at = <Date 2020-12-20.17:06:37.498>
user = 'https://bugs.python.org/AmundHov'

bugs.python.org fields:

activity = <Date 2020-12-20.17:06:37.498>
actor = 'iritkatriel'
assignee = 'none'
closed = True
closed_date = <Date 2020-12-20.17:06:37.498>
closer = 'iritkatriel'
components = ['Library (Lib)']
creation = <Date 2015-08-05.08:51:02.859>
creator = 'Amund Hov'
dependencies = []
files = []
hgrepos = []
issue_num = 24792
keywords = ['patch']
message_count = 2.0
messages = ['248022', '383334']
nosy_count = 8.0
nosy_names = ['twouters', 'gregory.p.smith', 'ncoghlan', 'eric.snow', 'superluser', 'Amund Hov', 'miss-islington', 'iritkatriel']
pr_nums = ['22204']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue24792'
versions = ['Python 3.10']

[AmundHov]

Due to mixed version .pyc files in my zipped python application I was getting inconsistent loading of certain packages.

E.g.

n [4]: zf.find_module('kitconsole')
Out[4]: <zipimporter object "test_controller_test.zip">

In [5]: zf.load_module('kitconsole')
---------------------------------------------------------------------------

ZipImportError                            Traceback (most recent call last)
<ipython-input-5-8e75885cc952> in <module>()
----> 1 zf.load_module('kitconsole')

ZipImportError: can't find module 'kitconsole'

Unpacking the archive and doing the import from the file system revealed the real issue, ImportError: Bad Magic Number.

As an end user it was confusing that zipimporter reported being able to find the module in find_module(), but not in load_module(). Is it possible to have load_module provide a better error message when import fails? The wording now does not give any hints when searching the bug-tracker / Google.

[miss-islington]

New changeset fb34096 by Irit Katriel in branch 'master':
bpo-24792: Fix zipimporter masking the cause of import errors (GH-22204)
fb34096