phase 3 bug repositories fixes

internal/domain/git/binary.go

@@ -45,6 +45,14 @@ func run(repoPath string, args ...string) ([]byte, error) {
 	return out, nil
 }
 
+// IsEmpty returns true when the repo has no commits yet.
+// Must use --verify: without it, rev-parse exits 0 in a bare empty repo
+// because HEAD is a valid symbolic ref even before the first commit.
+func IsEmpty(repoPath string) bool {
+	_, err := run(repoPath, "rev-parse", "--verify", "HEAD")
+	return err != nil
+}
+
 func Init(path string) error {
 	// git init --bare works even if the directory doesn't exist yet
 	cmd := exec.Command("git", "init", "--bare", path)
@@ -101,6 +109,10 @@ type TreeEntry struct {
 }
 
 func TreeLS(repoPath, ref, subPath string) ([]TreeEntry, error) {
+	// Short-circuit for repos with no commits yet.
+	if IsEmpty(repoPath) {
+		return nil, nil
+	}
 	treeRef := ref
 	if subPath != "" {
 		treeRef = ref + ":" + subPath