[Bug?]: patch-commit throws when git diff produces warnings

Self-service

• I'd be willing to implement a fix

Describe the bug

yarn patch-commit -s /tmp/folder fails if git diff writes warnings to stderr.

To reproduce

It's very simple:

1. yarn patch package
2. yarn patch-commit -s /tmp/xfs-some-random-chars/user

❯ yarn patch react-router
➤ YN0000: Package react-router@npm:8.3.1 got extracted with success!
➤ YN0000: You can now edit the following folder: /tmp/xfs-b87290bf/user
➤ YN0000: Once you are done run yarn patch-commit -s /tmp/xfs-b87290bf/user and Yarn will store a patchfile based on your changes.
➤ YN0000: Done in 0s 147ms

❯ yarn patch-commit -s /tmp/xfs-b87290bf/user
Internal Error: Unable to diff directories. Make sure you have a recent version of 'git' available in PATH.
The following error was reported by 'git':
warning: unable to access '/.config/git/attributes': Permission denied
warning: unable to access '/.config/git/attributes': Permission denied
warning: unable to access '/.config/git/attributes': Permission denied

The following error was reported by 'git':
warning: unable to access '/.config/git/attributes': Permission denied
warning: unable to access '/.config/git/attributes': Permission denied
warning: unable to access '/.config/git/attributes': Permission denied

    at xie (/home/manu/Projects/emanueleperuffo/emanueleperuffo-monorepo2/.yarn/releases/yarn-4.18.0.cjs:753:1455)
    at process.processTicksAndRejections (node:internal/process/task_queues:104:5)
    at async cv.execute (/home/manu/Projects/emanueleperuffo/emanueleperuffo-monorepo2/.yarn/releases/yarn-4.18.0.cjs:755:5218)
    at async cv.validateAndExecute (/home/manu/Projects/emanueleperuffo/emanueleperuffo-monorepo2/.yarn/releases/yarn-4.18.0.cjs:96:787)
    at async t.run (/home/manu/Projects/emanueleperuffo/emanueleperuffo-monorepo2/.yarn/releases/yarn-4.18.0.cjs:100:3263)
    at async Njt (/home/manu/Projects/emanueleperuffo/emanueleperuffo-monorepo2/.yarn/releases/yarn-4.18.0.cjs:773:8146)
    at async _O (/home/manu/Projects/emanueleperuffo/emanueleperuffo-monorepo2/.yarn/releases/yarn-4.18.0.cjs:774:142)

Environment

❯ yarn dlx -q envinfo --preset jest

  System:
    OS: Linux 7.1 cpe:/o:nixos:nixos:26.05 26.05 (Yarara)
    CPU: (4) x64 Intel(R) Core(TM) i7-7500U CPU @ 2.70GHz
  Binaries:
    Node: 24.19.0 - /tmp/xfs-0f115d47/node
    Yarn: 4.18.0 - /tmp/xfs-0f115d47/yarn
    npm: 11.19.0 - /home/manu/Projects/emanueleperuffo/emanueleperuffo-monorepo2/.devbox/nix/profile/default/bin/npm

I'm not sure why it shows node 24 because I'm in a devbox environment set up by direnv.

❯ node --version
v26.7.0

Additional context

I see that you consider the command failed if stderr is not empty. However those are warnings and not errors.

I tried to run the command that yarn runs directly in cli, first as is, and then by adding 2 more config overrides (-c core.hooksPath=/dev/null -c core.attributesFile=/dev/null) and those 2 config overrides (at least the attributes one, I've added the hooks one just in case) hide the warnings.

I have also tried patching the compiled release file in project/.yarn/releases/yarn-4.18.0.cjs adding those config overrides to the execvp call (await un.execvp("git",["-c","core.hooksPath=/dev/null","-c","core.attributesFile=/dev/null","-c",...) and it makes patch-commit work.

Command as run by yarn:

❯ PAGER="" GIT_CONFIG_NOSYSTEM="1" HOME="" XDG_CONFIG_HOME="" USERPROFILE="" git -c core.safecrlf=false -c core.quotePath=false diff --src-prefix=a/ --dst-prefix=b/ --ignore-cr-at-eol --full-index --no-index --no-renames --text /tmp/xfs-b87290bf/source /tmp/xfs-b87290bf/user
warning: unable to access '/.config/git/attributes': Permission denied
warning: unable to access '/.config/git/attributes': Permission denied
warning: unable to access '/.config/git/attributes': Permission denied
diff --git a/tmp/xfs-b87290bf/source/dist/development/index-react-server.js b/tmp/xfs-b87290bf/user/dist/development/index-react-server.js
index 2e9e07c2fdf31a30f3733dec8eb4b586697eeb53..b21c325ea30b5276812304f04df0dc3c459e8af8 100644
--- a/tmp/xfs-b87290bf/source/dist/development/index-react-server.js
+++ b/tmp/xfs-b87290bf/user/dist/development/index-react-server.js
@@ -502,7 +502,7 @@ function encodePathParam(value) {
 * @returns A path match object if the pattern matches the pathname,
 * or `null` if it does not match.
 */

Command with the 2 additional overrides (doesn't warn anymore):

❯ PAGER="" GIT_CONFIG_NOSYSTEM="1" HOME="" XDG_CONFIG_HOME="" USERPROFILE="" git -c core.hooksPath=/dev/null -c core.attributesFile=/dev/null -c core.safecrlf=false -c core.quotePath=false diff --src-prefix=a/ --dst-prefix=b/ --ignore-cr-at-eol --full-index --no-index --no-renames --text /tmp/xfs-b87290bf/source /tmp/xfs-b87290bf/user
diff --git a/tmp/xfs-b87290bf/source/dist/development/index-react-server.js b/tmp/xfs-b87290bf/user/dist/development/index-react-server.js
index 2e9e07c2fdf31a30f3733dec8eb4b586697eeb53..b21c325ea30b5276812304f04df0dc3c459e8af8 100644
--- a/tmp/xfs-b87290bf/source/dist/development/index-react-server.js
+++ b/tmp/xfs-b87290bf/user/dist/development/index-react-server.js
@@ -502,7 +502,7 @@ function encodePathParam(value) {
 * @returns A path match object if the pattern matches the pathname,
 * or `null` if it does not match.
 */

Start at the patch-commit command implementation and trace the Git diff invocation shown in the report. Reproduce with the provided yarn patch and yarn patch-commit commands, then verify that Git warnings on stderr no longer make the command fail while genuine diff errors still do.