refactor!: remove go-git backend (#39487)

Removes the go-git backend so every build uses the git CLI backend. Its
Windows performance advantage is gone, it lacks SHA-256 support, and it
breaks repositories on Windows.

The performance changes moved to
https://github.com/go-gitea/gitea/pull/39526.

Fixes https://github.com/go-gitea/gitea/issues/38359
Fixes https://github.com/go-gitea/gitea/issues/34694

---------

Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

modules/git/repo_branch_test.go

@@ -4,15 +4,9 @@
 package git
 
 import (
-	"fmt"
-	"os"
 	"path/filepath"
-	"strings"
 	"testing"
 
-	"gitea.dev/modules/git/gitcmd"
-	"gitea.dev/modules/setting"
-
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
@@ -45,41 +39,6 @@ func TestRepository_GetBranches(t *testing.T) {
 	assert.ElementsMatch(t, []string{}, branches)
 }
 
-// FIXME: covers the gogit workarounds in repo_base_gogit.go, remove with the gogit build
-func TestReadsAfterConcurrentRepack(t *testing.T) {
-	repoDir := t.TempDir()
-	require.NoError(t, gitcmd.NewCommand("init", "--bare").AddDynamicArguments(repoDir).Run(t.Context()))
-	content := strings.Repeat("a", int(setting.Git.LargeObjectThreshold)+1)
-	for _, from := range []string{"", "from refs/heads/main^0\n"} {
-		stdin := fmt.Sprintf("commit refs/heads/main\ncommitter a <a@a> 0 +0000\ndata 0\n%sM 100644 inline f\ndata %d\n%s\n", from, len(content), content)
-		require.NoError(t, gitcmd.NewCommand("fast-import").WithDir(repoDir).WithStdinBytes([]byte(stdin)).Run(t.Context()))
-		require.NoError(t, gitcmd.NewCommand("repack", "-d").WithDir(repoDir).Run(t.Context()))
-	}
-
-	repo, err := OpenRepositoryLocal(t.Context(), repoDir)
-	require.NoError(t, err)
-	defer repo.Close()
-	require.False(t, repo.IsObjectExist(t.Context(), "0000000000000000000000000000000000000001"))
-	blobRepo, err := OpenRepositoryLocal(t.Context(), repoDir)
-	require.NoError(t, err)
-	defer blobRepo.Close()
-	commit, err := blobRepo.GetBranchCommit(t.Context(), "main")
-	require.NoError(t, err)
-	readBlob := func() string {
-		data, err := commit.GetFileContent(t.Context(), blobRepo, "f", len(content))
-		require.NoError(t, err)
-		return data
-	}
-	require.Equal(t, content, readBlob())
-	require.NoError(t, gitcmd.NewCommand("repack", "-a", "-d").WithDir(repoDir).Run(t.Context()))
-	require.NoError(t, os.WriteFile(filepath.Join(repoDir, "objects", "pack", "pack-"+strings.Repeat("1", 40)+".pack"), nil, 0o644))
-
-	branches, _, err := repo.GetBranchNames(t.Context(), 0, 0)
-	require.NoError(t, err)
-	assert.Equal(t, []string{"main"}, branches)
-	assert.Equal(t, content, readBlob())
-}
-
 func BenchmarkRepository_GetBranches(b *testing.B) {
 	bareRepo1Path := filepath.Join(testReposDir, "repo1_bare")
 	bareRepo1, err := OpenRepositoryLocal(b.Context(), bareRepo1Path)
@@ -143,10 +102,6 @@ func TestRepository_IsObjectExist(t *testing.T) {
 	require.NoError(t, err)
 	defer repo.Close()
 
-	// FIXME: Inconsistent behavior between gogit and nogogit editions
-	// See the comment of IsObjectExist in gogit edition for more details.
-	supportShortHash := !isGogit
-
 	tests := []struct {
 		name string
 		arg  string
@@ -170,7 +125,7 @@ func TestRepository_IsObjectExist(t *testing.T) {
 		{
 			name: "short commit hash",
 			arg:  "ce06481",
-			want: supportShortHash,
+			want: true,
 		},
 		{
 			name: "blob hash",
@@ -180,7 +135,7 @@ func TestRepository_IsObjectExist(t *testing.T) {
 		{
 			name: "short blob hash",
 			arg:  "153f451",
-			want: supportShortHash,
+			want: true,
 		},
 	}
 	for _, tt := range tests {
@@ -196,10 +151,6 @@ func TestRepository_IsReferenceExist(t *testing.T) {
 	require.NoError(t, err)
 	defer repo.Close()
 
-	// FIXME: Inconsistent behavior between gogit and nogogit editions
-	// See the comment of IsReferenceExist in gogit edition for more details.
-	supportBlobHash := !isGogit
-
 	tests := []struct {
 		name string
 		arg  string
@@ -228,12 +179,12 @@ func TestRepository_IsReferenceExist(t *testing.T) {
 		{
 			name: "blob hash",
 			arg:  "153f451b9ee7fa1da317ab17a127e9fd9d384310",
-			want: supportBlobHash,
+			want: true,
 		},
 		{
 			name: "short blob hash",
 			arg:  "153f451",
-			want: supportBlobHash,
+			want: true,
 		},
 	}
 	for _, tt := range tests {