test: add cmd/bd helper coverage and stabilize test runner

Co-authored-by: factory-droid[bot] <138933559+factory-droid[bot]@users.noreply.github.com>

cmd/bd/test_wait_helper.go

@@ -5,6 +5,8 @@ import (
 	"os/exec"
 	"testing"
 	"time"
+
+	"github.com/steveyegge/beads/internal/git"
 )
 
 // waitFor repeatedly evaluates pred until it returns true or timeout expires.
@@ -42,6 +44,7 @@ func setupGitRepo(t *testing.T) (repoPath string, cleanup func()) {
 		_ = os.Chdir(originalWd)
 		t.Fatalf("failed to init git repo: %v", err)
 	}
+	git.ResetCaches()
 
 	// Configure git
 	_ = exec.Command("git", "config", "user.email", "test@test.com").Run()
@@ -85,6 +88,7 @@ func setupGitRepoWithBranch(t *testing.T, branch string) (repoPath string, clean
 		_ = os.Chdir(originalWd)
 		t.Fatalf("failed to init git repo: %v", err)
 	}
+	git.ResetCaches()
 
 	// Configure git
 	_ = exec.Command("git", "config", "user.email", "test@test.com").Run()