test/shamhub: Scope bare-repo git commands with --git-dir

internal/forge/shamhub/change.go

@@ -7,7 +7,6 @@ import (
 	"strings"
 
 	"go.abhg.dev/gs/internal/forge"
-	"go.abhg.dev/gs/internal/xec"
 )
 
 // ListChanges reports all changes known to the forge.
@@ -222,8 +221,7 @@ type ChangeBranch struct {
 }
 
 func (sh *ShamHub) toChangeBranch(b *shamBranch) (*ChangeBranch, error) {
-	out, err := xec.Command(context.Background(), sh.log, sh.gitExe, "rev-parse", b.Name).
-		WithDir(sh.repoDir(b.Owner, b.Repo)).
+	out, err := sh.gitCmd(context.Background(), b.Owner, b.Repo, "rev-parse", b.Name).
 		Output()
 	if err != nil {
 		return nil, fmt.Errorf("get SHA for %v/%v:%v: %w", b.Owner, b.Repo, b.Name, err)

internal/forge/shamhub/ref.go

@@ -3,8 +3,6 @@ package shamhub
 import (
 	"context"
 	"fmt"
-
-	"go.abhg.dev/gs/internal/xec"
 )
 
 type refExistsRequest struct {
@@ -38,8 +36,7 @@ func (r *forgeRepository) RefExists(ctx context.Context, ref string) (bool, erro
 }
 
 func (sh *ShamHub) refExists(ctx context.Context, owner, repo, ref string) bool {
-	return xec.Command(ctx, sh.log, sh.gitExe, "show-ref", "--verify", "--quiet", ref).
-		WithDir(sh.repoDir(owner, repo)).
+	return sh.gitCmd(ctx, owner, repo, "show-ref", "--verify", "--quiet", ref).
 		Run() == nil
 }
 

internal/forge/shamhub/repo.go

@@ -98,8 +98,7 @@ func (sh *ShamHub) newRepository(owner, repo string, forkOf *repoID) (string, er
 	}
 
 	// Configure the repository to accept pushes.
-	if err := xec.Command(ctx, sh.log, sh.gitExe, "config", "http.receivepack", "true").
-		WithDir(repoDir).
+	if err := sh.gitCmd(ctx, owner, repo, "config", "http.receivepack", "true").
 		CaptureStdout().
 		Run(); err != nil {
 		return "", fmt.Errorf("configure repository: %w", err)

internal/forge/shamhub/shamhub.go

@@ -5,6 +5,7 @@
 package shamhub
 
 import (
+	"context"
 	"fmt"
 	"net/http/cgi"
 	"net/http/httptest"
@@ -137,6 +138,16 @@ func (sh *ShamHub) repoDir(owner, repo string) string {
 	return filepath.Join(sh.gitRoot, owner, repo+".git")
 }
 
+// gitCmd builds a git command scoped to the bare repository for owner/repo.
+// Use this instead of WithDir(repoDir(...)): git 2.50 no longer discovers a
+// bare repo from the current working directory alone, so an explicit
+// --git-dir is required for `git config`, `git show-ref`, `git rev-parse`,
+// and similar commands.
+func (sh *ShamHub) gitCmd(ctx context.Context, owner, repo string, args ...string) *xec.Cmd {
+	return xec.Command(ctx, sh.log, sh.gitExe,
+		append([]string{"--git-dir", sh.repoDir(owner, repo)}, args...)...)
+}
+
 func (sh *ShamHub) changeURL(owner, repo string, change int) string {
 	return fmt.Sprintf("%s/%s/%s/change/%d", sh.GitURL(), owner, repo, change)
 }

internal/forge/shamhub/states.go

@@ -10,7 +10,6 @@ import (
 
 	"go.abhg.dev/gs/internal/forge"
 	"go.abhg.dev/gs/internal/git"
-	"go.abhg.dev/gs/internal/xec"
 )
 
 type statesRequest struct {
@@ -208,23 +207,17 @@ func (sh *ShamHub) MergeChange(req MergeChangeRequest) error {
 		return fmt.Errorf("change %d (%v/%v) is not open", req.Number, req.Owner, req.Repo)
 	}
 
-	// Determine if this is a cross-fork merge by checking if the head branch
-	// exists in the target repository or needs to be fetched from a fork
-	targetRepoDir := sh.repoDir(req.Owner, req.Repo)
-
 	baseRef := change.Base
 	headRef := change.Head
 
 	ctx, cancel := context.WithCancel(context.Background())
 	defer cancel()
 
 	if req.Time.IsZero() {
-		out, err := xec.Command(
-			ctx, sh.log, sh.gitExe,
+		out, err := sh.gitCmd(
+			ctx, headRef.Owner, headRef.Repo,
 			"log", "-1", "--format=%cI", headRef.Name,
-		).
-			WithDir(sh.repoDir(headRef.Owner, headRef.Repo)).
-			Output()
+		).Output()
 		if err != nil {
 			return fmt.Errorf("read head commit time: %w", err)
 		}
@@ -246,10 +239,8 @@ func (sh *ShamHub) MergeChange(req MergeChangeRequest) error {
 
 	// If a HeadHash is provided, verify the head matches.
 	if req.HeadHash != "" {
-		headRepoDir := sh.repoDir(headRef.Owner, headRef.Repo)
-		out, err := xec.Command(ctx, sh.log, sh.gitExe,
+		out, err := sh.gitCmd(ctx, headRef.Owner, headRef.Repo,
 			"rev-parse", headRef.Name).
-			WithDir(headRepoDir).
 			Output()
 		if err != nil {
 			return fmt.Errorf("resolve head ref: %w", err)
@@ -267,8 +258,7 @@ func (sh *ShamHub) MergeChange(req MergeChangeRequest) error {
 	if headRef.Owner != req.Owner || headRef.Repo != req.Repo {
 		// Fetch the head branch from the fork
 		forkRepoDir := sh.repoDir(headRef.Owner, headRef.Repo)
-		if err := xec.Command(ctx, sh.log, sh.gitExe, "fetch", forkRepoDir, headRef.Name+":"+headRef.Name).
-			WithDir(targetRepoDir).
+		if err := sh.gitCmd(ctx, req.Owner, req.Repo, "fetch", forkRepoDir, headRef.Name+":"+headRef.Name).
 			Run(); err != nil {
 			return fmt.Errorf("fetch from fork: %w", err)
 		}
@@ -284,8 +274,7 @@ func (sh *ShamHub) MergeChange(req MergeChangeRequest) error {
 	//
 	// This requires at least Git 2.38.
 	tree, err := func() (string, error) {
-		out, err := xec.Command(ctx, sh.log, sh.gitExe, "merge-tree", "--write-tree", baseRef.Name, headRef.Name).
-			WithDir(targetRepoDir).
+		out, err := sh.gitCmd(ctx, req.Owner, req.Repo, "merge-tree", "--write-tree", baseRef.Name, headRef.Name).
 			Output()
 		if err != nil {
 			return "", fmt.Errorf("merge-tree: %w", err)
@@ -313,8 +302,7 @@ func (sh *ShamHub) MergeChange(req MergeChangeRequest) error {
 		}
 		args = append(args, "-m", msg, tree)
 
-		out, err := xec.Command(ctx, sh.log, sh.gitExe, args...).
-			WithDir(sh.repoDir(req.Owner, req.Repo)).
+		out, err := sh.gitCmd(ctx, req.Owner, req.Repo, args...).
 			AppendEnv(commitEnv...).
 			Output()
 		if err != nil {
@@ -328,8 +316,7 @@ func (sh *ShamHub) MergeChange(req MergeChangeRequest) error {
 	}
 
 	headHash, err := func() (string, error) {
-		out, err := xec.Command(ctx, sh.log, sh.gitExe, "rev-parse", headRef.Name).
-			WithDir(sh.repoDir(headRef.Owner, headRef.Repo)).
+		out, err := sh.gitCmd(ctx, headRef.Owner, headRef.Repo, "rev-parse", headRef.Name).
 			Output()
 		if err != nil {
 			return "", fmt.Errorf("rev-parse head: %w", err)
@@ -344,8 +331,7 @@ func (sh *ShamHub) MergeChange(req MergeChangeRequest) error {
 	// Update the ref to point to the new commit.
 	err = func() error {
 		ref := "refs/heads/" + sh.changes[changeIdx].Base.Name
-		if err := xec.Command(ctx, sh.log, sh.gitExe, "update-ref", ref, commit).
-			WithDir(sh.repoDir(req.Owner, req.Repo)).
+		if err := sh.gitCmd(ctx, req.Owner, req.Repo, "update-ref", ref, commit).
 			Run(); err != nil {
 			return fmt.Errorf("update-ref: %w", err)
 		}
@@ -358,8 +344,7 @@ func (sh *ShamHub) MergeChange(req MergeChangeRequest) error {
 
 	if req.DeleteBranch {
 		err := func() error {
-			if err := xec.Command(ctx, sh.log, sh.gitExe, "branch", "-D", change.Head.Name).
-				WithDir(sh.repoDir(change.Head.Owner, change.Head.Repo)).
+			if err := sh.gitCmd(ctx, change.Head.Owner, change.Head.Repo, "branch", "-D", change.Head.Name).
 				Run(); err != nil {
 				return fmt.Errorf("delete branch: %w", err)
 			}

internal/forge/shamhub/template.go

@@ -9,7 +9,6 @@ import (
 
 	"go.abhg.dev/gs/internal/forge"
 	"go.abhg.dev/gs/internal/scanutil"
-	"go.abhg.dev/gs/internal/xec"
 )
 
 var _changeTemplatePaths = []string{
@@ -49,9 +48,8 @@ func (sh *ShamHub) handleChangeTemplate(ctx context.Context, req *changeTemplate
 
 	var res changeTemplateResponse
 	var matches []matchingTemplatePath
-	treeCmd := xec.Command(ctx, nil, sh.gitExe,
-		"ls-tree", "-r", "-z", "--name-only", "HEAD").
-		WithDir(sh.repoDir(owner, repo))
+	treeCmd := sh.gitCmd(ctx, owner, repo,
+		"ls-tree", "-r", "-z", "--name-only", "HEAD")
 	for treePath, err := range treeCmd.Scan(scanutil.SplitNull) {
 		if err != nil {
 			return nil, nil
@@ -69,9 +67,8 @@ func (sh *ShamHub) handleChangeTemplate(ctx context.Context, req *changeTemplate
 	})
 
 	for _, templatePath := range matches {
-		out, err := xec.Command(ctx, sh.log, sh.gitExe,
+		out, err := sh.gitCmd(ctx, owner, repo,
 			"cat-file", "blob", "HEAD:"+templatePath.filePath).
-			WithDir(sh.repoDir(owner, repo)).
 			Output()
 		if err != nil {
 			continue