fix: walk git log context error handling (#38182)

Fix #38177

Make WalkGitLog can handle EOF and context errors correctly, and don't
export these private functions & methods & structs.

modules/git/commit_info_nogogit_test.go

@@ -0,0 +1,54 @@
+// Copyright 2026 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+//go:build !gogit
+
+package git
+
+import (
+	"context"
+	"path/filepath"
+	"testing"
+
+	"gitea.dev/modules/test"
+	"gitea.dev/modules/util"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestEntries_GetCommitsInfo_ContextErr(t *testing.T) {
+	repo, err := OpenRepository(t.Context(), filepath.Join(testReposDir, "repo1_bare"))
+	require.NoError(t, err)
+	defer repo.Close()
+
+	commit, err := repo.GetCommit("feaf4ba6bc635fec442f46ddd4512416ec43c2c2")
+	require.NoError(t, err)
+	entries, err := commit.Tree.ListEntries()
+	require.NoError(t, err)
+
+	countCommitInfosCommit := func(infos []CommitInfo) (nilCommits, nonNilCommits int) {
+		for _, info := range infos {
+			nilCommits += util.Iif(info.Commit == nil, 1, 0)
+			nonNilCommits += util.Iif(info.Commit != nil, 1, 0)
+		}
+		return nilCommits, nonNilCommits
+	}
+
+	ctx, cancel := context.WithCancel(t.Context())
+	defer test.MockVariableValue(&walkGitLogDebugBeforeNext)()
+
+	walkGitLogDebugBeforeNext = cancel
+	commitInfos, _, err := entries.GetCommitsInfo(ctx, "/any/repo-link", commit, "")
+	assert.NoError(t, err)
+	nilCommits, nonNilCommits := countCommitInfosCommit(commitInfos)
+	assert.Equal(t, 0, nonNilCommits) // no commit info due to canceled (or deadline-exceeded) context
+	assert.Equal(t, 3, nilCommits)
+
+	walkGitLogDebugBeforeNext = nil
+	commitInfos, _, err = entries.GetCommitsInfo(t.Context(), "/any/repo-link", commit, "")
+	assert.NoError(t, err)
+	nilCommits, nonNilCommits = countCommitInfosCommit(commitInfos)
+	assert.Equal(t, 3, nonNilCommits)
+	assert.Equal(t, 0, nilCommits)
+}