Improve error output when a command fails

[hugovk]

Fixes#100.

Sometimes cherry-picker fails and it really doesn't tell you why:

Uninformative error

❯ cherry_picker --continue
🐍 🍒 ⛏
Traceback (most recent call last):
File "/Library/Frameworks/Python.framework/Versions/3.14/bin/cherry_picker", line 10, in <module>
sys.exit(cherry_pick_cli())
~~~~~~~~~~~~~~~^^
File "/Library/Frameworks/Python.framework/Versions/3.14/lib/python3.14/site-packages/click/core.py", line 1485, in __call__returnself.main(*args, **kwargs)
~~~~~~~~~^^^^^^^^^^^^^^^^^
File "/Library/Frameworks/Python.framework/Versions/3.14/lib/python3.14/site-packages/click/core.py", line 1406, in main
rv =self.invoke(ctx)
File "/Library/Frameworks/Python.framework/Versions/3.14/lib/python3.14/site-packages/click/core.py", line 1269, in invokereturn ctx.invoke(self.callback, **ctx.params)
~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/Library/Frameworks/Python.framework/Versions/3.14/lib/python3.14/site-packages/click/core.py", line 824, in invokereturn callback(*args, **kwargs)
File "/Library/Frameworks/Python.framework/Versions/3.14/lib/python3.14/site-packages/click/decorators.py", line 34, in new_funcreturn f(get_current_context(), *args, **kwargs)
File "/Library/Frameworks/Python.framework/Versions/3.14/lib/python3.14/site-packages/cherry_picker/cherry_picker.py", line 855, in cherry_pick_cli
cherry_picker.continue_cherry_pick()
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^
File "/Library/Frameworks/Python.framework/Versions/3.14/lib/python3.14/site-packages/cherry_picker/cherry_picker.py", line 657, in continue_cherry_pickself.run_cmd(cmd)
~~~~~~~~~~~~^^^^^
File "/Library/Frameworks/Python.framework/Versions/3.14/lib/python3.14/site-packages/cherry_picker/cherry_picker.py", line 236, in run_cmd
output = subprocess.check_output(cmd, stderr=subprocess.STDOUT)
File "/Library/Frameworks/Python.framework/Versions/3.14/lib/python3.14/subprocess.py", line 472, in check_outputreturn run(*popenargs, stdout=PIPE, timeout=timeout, check=True,
~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^**kwargs).stdout
^^^^^^^^^
File "/Library/Frameworks/Python.framework/Versions/3.14/lib/python3.14/subprocess.py", line 577, in runraise CalledProcessError(retcode, process.args,
output=stdout, stderr=stderr)
subprocess.CalledProcessError: Command '['git', 'commit', '-a', '-m', '[3.14] gh-146488: hash-pin all action references\n(cherry picked from commit a504c0a590b9379688e4718225efb361b94cc4a1)\n\nCo-authored-by: William Woodruff <william@yossarian.net>\nSigned-off-by: William Woodruff <william@yossarian.net>', '--allow-empty']' returned non-zero exit status 1.

I have no idea what is wrong from the above. I reset, resolved my conflict and tried again. Same error.

But sometimes this is caused by git commit failing. It helps to show what actually went wrong:

Details

❯ cherry_picker --continue
🐍 🍒 ⛏
Run Ruff (lint) on Apple/............................(no files to check)Skipped
Run Ruff (lint) on Doc/..............................(no files to check)Skipped
Run Ruff (lint) on Lib/test/.........................(no files to check)Skipped
Run Ruff (lint) on Tools/build/......................(no files to check)Skipped
Run Ruff (lint) on Tools/i18n/.......................(no files to check)Skipped
Run Ruff (lint) on Argument Clinic...................(no files to check)Skipped
Run Ruff (lint) on Tools/peg_generator/..............(no files to check)Skipped
Run Ruff (lint) on Tools/wasm/.......................(no files to check)Skipped
Run Ruff (format) on Apple/..........................(no files to check)Skipped
Run Ruff (format) on Doc/............................(no files to check)Skipped
Run Ruff (format) on Tools/build/check_warnings.py...(no files to check)Skipped
Run Ruff (format) on Tools/wasm/.....................(no files to check)Skipped
Run Black on Tools/jit/..............................(no files to check)Skipped
Tabs remover.........................................(no files to check)Skipped
check for case conflicts.................................................Passed
check for merge conflicts................................................Passed
check toml...........................................(no files to check)Skipped
check yaml...............................................................Passed
fix end of files.........................................................Passed
fix end of files.....................................(no files to check)Skipped
trim trailing whitespace.................................................Passed
trim trailing whitespace.............................(no files to check)Skipped
Validate Dependabot Config (v2)......................(no files to check)Skipped
Validate GitHub Workflows................................................Passed
Validate ReadTheDocs Config..........................(no files to check)Skipped
Lint GitHub Actions workflow files.......................................Passed
zizmor...................................................................Failed
- hook id: zizmor
- exit code: 14
error[unpinned-uses]: unpinned action reference
--> .github/workflows/reusable-cifuzz.yml:24:15|
24 | uses: google/oss-fuzz/infra/cifuzz/actions/build_fuzzers@master
|^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ action isnot pinned to a hash (required by blanket policy)
|= note: audit confidence → High
=help: audit documentation → https://docs.zizmor.sh/audits/#unpinned-uses
error[unpinned-uses]: unpinned action reference
--> .github/workflows/reusable-cifuzz.yml:29:15|
29 | uses: google/oss-fuzz/infra/cifuzz/actions/run_fuzzers@master
|^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ action isnot pinned to a hash (required by blanket policy)
|= note: audit confidence → High
=help: audit documentation → https://docs.zizmor.sh/audits/#unpinned-uses
117 findings (4 ignored, 111 suppressed): 0 informational, 0 low, 0 medium, 2 high
🌈 zizmor v1.22.0
INFO audit: zizmor: 🌈 completed .github/workflows/add-issue-header.yml
INFO audit: zizmor: 🌈 completed .github/workflows/build.yml
INFO audit: zizmor: 🌈 completed .github/workflows/documentation-links.yml
WARN audit: zizmor: one or more inputs contains YAML anchors; you may encounter crashes or unpredictable behavior
WARN audit: zizmor: for more information, see: https://docs.zizmor.sh/usage/#yaml-anchors
INFO audit: zizmor: 🌈 completed .github/workflows/jit.yml
INFO audit: zizmor: 🌈 completed .github/workflows/lint.yml
INFO audit: zizmor: 🌈 completed .github/workflows/mypy.yml
INFO audit: zizmor: 🌈 completed .github/workflows/new-bugs-announce-notifier.yml
INFO audit: zizmor: 🌈 completed .github/workflows/project-updater.yml
INFO audit: zizmor: 🌈 completed .github/workflows/require-pr-label.yml
INFO audit: zizmor: 🌈 completed .github/workflows/reusable-cifuzz.yml
INFO audit: zizmor: 🌈 completed .github/workflows/reusable-context.yml
INFO audit: zizmor: 🌈 completed .github/workflows/reusable-docs.yml
INFO audit: zizmor: 🌈 completed .github/workflows/reusable-emscripten.yml
INFO audit: zizmor: 🌈 completed .github/workflows/reusable-macos.yml
INFO audit: zizmor: 🌈 completed .github/workflows/reusable-san.yml
INFO audit: zizmor: 🌈 completed .github/workflows/reusable-ubuntu.yml
INFO audit: zizmor: 🌈 completed .github/workflows/reusable-wasi.yml
INFO audit: zizmor: 🌈 completed .github/workflows/reusable-windows-msi.yml
INFO audit: zizmor: 🌈 completed .github/workflows/reusable-windows.yml
INFO audit: zizmor: 🌈 completed .github/workflows/stale.yml
INFO audit: zizmor: 🌈 completed .github/workflows/tail-call.yml
INFO audit: zizmor: 🌈 completed .github/workflows/verify-ensurepip-wheels.yml
INFO audit: zizmor: 🌈 completed .github/workflows/verify-expat.yml
Sphinx Lint..........................................(no files to check)Skipped
Check C API news entries.............................(no files to check)Skipped
Check Core and Builtins news entries.................(no files to check)Skipped
Check hooks apply....................................(no files to check)Skipped
Check useless excludes...............................(no files to check)Skipped
Traceback (most recent call last):
File "/Library/Frameworks/Python.framework/Versions/3.14/bin/cherry_picker", line 10, in <module>
sys.exit(cherry_pick_cli())
~~~~~~~~~~~~~~~^^
File "/Library/Frameworks/Python.framework/Versions/3.14/lib/python3.14/site-packages/click/core.py", line 1485, in __call__returnself.main(*args, **kwargs)
~~~~~~~~~^^^^^^^^^^^^^^^^^
File "/Library/Frameworks/Python.framework/Versions/3.14/lib/python3.14/site-packages/click/core.py", line 1406, in main
rv =self.invoke(ctx)
File "/Library/Frameworks/Python.framework/Versions/3.14/lib/python3.14/site-packages/click/core.py", line 1269, in invokereturn ctx.invoke(self.callback, **ctx.params)
~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/Library/Frameworks/Python.framework/Versions/3.14/lib/python3.14/site-packages/click/core.py", line 824, in invokereturn callback(*args, **kwargs)
File "/Library/Frameworks/Python.framework/Versions/3.14/lib/python3.14/site-packages/click/decorators.py", line 34, in new_funcreturn f(get_current_context(), *args, **kwargs)
File "/Users/hugo/github/cherry-picker/cherry_picker/cherry_picker.py", line 859, in cherry_pick_cli
cherry_picker.continue_cherry_pick()
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^
File "/Users/hugo/github/cherry-picker/cherry_picker/cherry_picker.py", line 661, in continue_cherry_pickself.run_cmd(cmd)
~~~~~~~~~~~~^^^^^
File "/Users/hugo/github/cherry-picker/cherry_picker/cherry_picker.py", line 237, in run_cmd
output = subprocess.check_output(cmd, stderr=subprocess.STDOUT)
File "/Library/Frameworks/Python.framework/Versions/3.14/lib/python3.14/subprocess.py", line 472, in check_outputreturn run(*popenargs, stdout=PIPE, timeout=timeout, check=True,
~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^**kwargs).stdout
^^^^^^^^^
File "/Library/Frameworks/Python.framework/Versions/3.14/lib/python3.14/subprocess.py", line 577, in runraise CalledProcessError(retcode, process.args,
output=stdout, stderr=stderr)
subprocess.CalledProcessError: Command '['git', 'commit', '-a', '-m', '[3.14] gh-146488: hash-pin all action references\n(cherry picked from commit a504c0a590b9379688e4718225efb361b94cc4a1)\n\nCo-authored-by: William Woodruff <william@yossarian.net>\nSigned-off-by: William Woodruff <william@yossarian.net>', '--allow-empty']' returned non-zero exit status 1.

Aha! In this case, I can see pre-commit found an action that wasn't pinned, and the whole point of my backport is to pin them! I now know what to do!

[Mariatta]

Thanks.