Auto merge of #29539 - mrobinson:more-debugging-for-wpt-upstreamer, r=delan

Be more verbose when a command fails in the WPT upstream script

This should make it easier to debug the strange script failures we are seeing on some
PRs such as the [one seen here](https://github.com/servo/servo/pull/29396/#issuecomment-1480919565).

---
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- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [x] These changes do not require tests because this just increases debugging output.

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etc/ci/upstream-wpt-changes/wptupstreamer/__init__.py

@@ -60,9 +60,14 @@ class LocalGitRepo:
         env.setdefault("GIT_AUTHOR_NAME", self.sync.github_name)
         env.setdefault("GIT_COMMITTER_NAME", self.sync.github_name)
 
-        return subprocess.check_output(
-            command_line, cwd=self.path, env=env, stderr=subprocess.STDOUT
-        ).decode("utf-8")
+        try:
+            return subprocess.check_output(
+                command_line, cwd=self.path, env=env, stderr=subprocess.STDOUT
+            ).decode("utf-8")
+        except subprocess.CalledProcessError as exception:
+            logging.warning("Process execution failed with output:\n%s",
+                            exception.output.decode("utf-8"))
+            raise exception
 
 
 @dataclasses.dataclass()