gh-104372: use == -1 before PyErr_Occurred

[gpshead]

The ideal pattern for this. (already in the 3.11 backport)

• Issue: subprocess can block all Python threads when using vfork() until the child process exec() succeeds or fails. #104372

[miss-islington]

Thanks @gpshead for the PR 🌮🎉.. I'm working now to backport this PR to: 3.12.
🐍🍒⛏🤖

[bedevere-bot]

GH-104833 is a backport of this pull request to the 3.12 branch.

[bedevere-bot]

⚠️⚠️⚠️ Buildbot failure ⚠️⚠️⚠️

Hi! The buildbot AMD64 Ubuntu Shared 3.x has failed when building commit 7f963bf.

What do you need to do:

1. Don't panic.
2. Check the buildbot page in the devguide if you don't know what the buildbots are or how they work.
3. Go to the page of the buildbot that failed (https://buildbot.python.org/all/#builders/506/builds/4875) and take a look at the build logs.
4. Check if the failure is related to this commit (7f963bf) or if it is a false positive.
5. If the failure is related to this commit, please, reflect that on the issue and make a new Pull Request with a fix.

You can take a look at the buildbot page here:

https://buildbot.python.org/all/#builders/506/builds/4875

Summary of the results of the build (if available):

== Tests result: ENV CHANGED ==

442 tests OK.

10 slowest tests:

• test_tools: 5 min 55 sec
• test_multiprocessing_spawn: 3 min 46 sec
• test_math: 3 min 36 sec
• test_concurrent_futures: 2 min 57 sec
• test_gdb: 2 min 48 sec
• test_multiprocessing_forkserver: 1 min 48 sec
• test_unparse: 1 min 35 sec
• test_compileall: 1 min 24 sec
• test_capi: 1 min 21 sec
• test_multiprocessing_fork: 1 min 15 sec

1 test altered the execution environment:
test_importlib

22 tests skipped:
test.test_asyncio.test_windows_events
test.test_asyncio.test_windows_utils test_devpoll test_idle
test_ioctl test_kqueue test_launcher test_msilib test_nis
test_peg_generator test_startfile test_tcl test_tix test_tkinter
test_ttk test_ttk_textonly test_turtle test_winconsoleio
test_winreg test_winsound test_wmi test_zipfile64

Total duration: 27 min 57 sec

Click to see traceback logs

remote: Enumerating objects: 7, done.        
remote: Counting objects:  14% (1/7)        
remote: Counting objects:  28% (2/7)        
remote: Counting objects:  42% (3/7)        
remote: Counting objects:  57% (4/7)        
remote: Counting objects:  71% (5/7)        
remote: Counting objects:  85% (6/7)        
remote: Counting objects: 100% (7/7)        
remote: Counting objects: 100% (7/7), done.        
remote: Compressing objects: 100% (1/1)        
remote: Compressing objects: 100% (1/1), done.        
remote: Total 4 (delta 3), reused 4 (delta 3), pack-reused 0        
From https://github.com/python/cpython
 * branch                  main       -> FETCH_HEAD
Note: switching to '7f963bfc79a515dc9822ebddbfb1b5927d2dda09'.

You are in 'detached HEAD' state. You can look around, make experimental
changes and commit them, and you can discard any commits you make in this
state without impacting any branches by switching back to a branch.

If you want to create a new branch to retain commits you create, you may
do so (now or later) by using -c with the switch command. Example:

  git switch -c <new-branch-name>

Or undo this operation with:

  git switch -

Turn off this advice by setting config variable advice.detachedHead to false

HEAD is now at 7f963bfc79 gh-104372: use == -1 before PyErr_Occurred (#104831)
Switched to and reset branch 'main'

./configure: line 8401: -reorder-blocks=ext-tsp: command not found
configure: WARNING: pkg-config is missing. Some dependencies may not be detected correctly.

make: *** [Makefile:2011: buildbottest] Error 3

[bedevere-bot]

⚠️⚠️⚠️ Buildbot failure ⚠️⚠️⚠️

Hi! The buildbot AMD64 Arch Linux TraceRefs 3.x has failed when building commit 7f963bf.

What do you need to do:

1. Don't panic.
2. Check the buildbot page in the devguide if you don't know what the buildbots are or how they work.
3. Go to the page of the buildbot that failed (https://buildbot.python.org/all/#builders/484/builds/3377) and take a look at the build logs.
4. Check if the failure is related to this commit (7f963bf) or if it is a false positive.
5. If the failure is related to this commit, please, reflect that on the issue and make a new Pull Request with a fix.

You can take a look at the buildbot page here:

https://buildbot.python.org/all/#builders/484/builds/3377

Failed tests:

• test__xxsubinterpreters

Summary of the results of the build (if available):

==

Click to see traceback logs

remote: Enumerating objects: 4, done.        
remote: Counting objects:  25% (1/4)        
remote: Counting objects:  50% (2/4)        
remote: Counting objects:  75% (3/4)        
remote: Counting objects: 100% (4/4)        
remote: Counting objects: 100% (4/4), done.        
remote: Compressing objects:  33% (1/3)        
remote: Compressing objects:  66% (2/3)        
remote: Compressing objects: 100% (3/3)        
remote: Compressing objects: 100% (3/3), done.        
remote: Total 4 (delta 1), reused 3 (delta 1), pack-reused 0        
From https://github.com/python/cpython
 * branch                  main       -> FETCH_HEAD
Note: switching to '7f963bfc79a515dc9822ebddbfb1b5927d2dda09'.

You are in 'detached HEAD' state. You can look around, make experimental
changes and commit them, and you can discard any commits you make in this
state without impacting any branches by switching back to a branch.

If you want to create a new branch to retain commits you create, you may
do so (now or later) by using -c with the switch command. Example:

  git switch -c <new-branch-name>

Or undo this operation with:

  git switch -

Turn off this advice by setting config variable advice.detachedHead to false

HEAD is now at 7f963bfc79 gh-104372: use == -1 before PyErr_Occurred (#104831)
Switched to and reset branch 'main'

./configure: line 8401: -reorder-blocks=ext-tsp: command not found

Objects/object.c:2211: _Py_ForgetReference: Assertion failed: invalid object chain
Enable tracemalloc to get the memory block allocation traceback

object address  : 0x7f97d5d15300
object refcount : 0
object type     : 0x55ffd0d0d8c0
object type name: bytes
object repr     : <refcnt 0 at 0x7f97d5d15300>

Fatal Python error: _PyObject_AssertFailed: _PyObject_AssertFailed
Python runtime state: initialized

Current thread 0x00007f97e816a740 (most recent call first):
  <no Python frame>

Extension modules: _xxsubinterpreters (total: 1)
Debug memory block at address p=0x7f97e8091e30: API '�'
    18302063728033390045 bytes originally requested
    The 7 pad bytes at p-7 are not all FORBIDDENBYTE (0xfd):
        at p-7: 0xdd *** OUCH
        at p-6: 0xdd *** OUCH
        at p-5: 0xdd *** OUCH
        at p-4: 0xdd *** OUCH
        at p-3: 0xdd *** OUCH
        at p-2: 0xdd *** OUCH
        at p-1: 0xdd *** OUCH
    Because memory is corrupted at the start, the count of bytes requested
       may be bogus, and checking the trailing pad bytes may segfault.
    The 8 pad bytes at tail=0xfdfe7d95e606fc0d are Fatal Python error: Segmentation fault

Current thread 0x00007f97e816a740 (most recent call first):
  <no Python frame>

Extension modules: _testcapi, _xxsubinterpreters (total: 2)
make: *** [Makefile:2015: buildbottest] Segmentation fault (core dumped)

Cannot open file '/buildbot/buildarea/3.x.pablogsal-arch-x86_64/build/test-results.xml' for upload