debug diff issues

Author: dmcilvaney

.github/workflows/scripts/check_rendered_specs.py

@@ -281,7 +281,7 @@ def generate_patch(
 
     pathspec_fd, pathspec_path = tempfile.mkstemp(prefix="render-check-", suffix=".txt")
     with os.fdopen(pathspec_fd, "w") as f:
-        f.write("\n".join(paths))
+        f.write("\n".join(paths) + "\n")
 
     extra_pathspec_path: str | None = None
     try:
@@ -291,12 +291,19 @@ def generate_patch(
                 prefix="render-check-extra-", suffix=".txt"
             )
             with os.fdopen(extra_fd, "w") as f:
-                f.write("\n".join(extra_files))
-            subprocess.run(
-                ["git", "add", "-N", "--pathspec-from-file", extra_pathspec_path],
-                check=True,
-                capture_output=True,
-            )
+                f.write("\n".join(extra_files) + "\n")
+            try:
+                subprocess.run(
+                    ["git", "add", "-N", "--pathspec-from-file", extra_pathspec_path],
+                    check=True,
+                    capture_output=True,
+                )
+            except subprocess.CalledProcessError as exc:
+                stderr = (exc.stderr or b"").decode("utf-8", errors="replace").strip()
+                print(
+                    f"::warning::git add -N failed: exit={exc.returncode}: {stderr}",
+                    file=sys.stderr,
+                )
 
         try:
             result = subprocess.run(
@@ -306,8 +313,9 @@ def generate_patch(
             )
             patch = result.stdout
         except subprocess.CalledProcessError as exc:
+            stderr = (exc.stderr or b"").decode("utf-8", errors="replace").strip()
             print(
-                f"::warning::git diff failed while generating patch: {exc}",
+                f"::warning::git diff failed while generating patch: exit={exc.returncode}: {stderr}",
                 file=sys.stderr,
             )
             patch = b""
@@ -321,8 +329,9 @@ def generate_patch(
                     capture_output=True,
                 )
             except subprocess.CalledProcessError as exc:
+                stderr = (exc.stderr or b"").decode("utf-8", errors="replace").strip()
                 print(
-                    f"::warning::git reset (undo intent-to-add) failed: {exc}",
+                    f"::warning::git reset (undo intent-to-add) failed: exit={exc.returncode}: {stderr}",
                     file=sys.stderr,
                 )
             finally: