Cupertino bottom sheet broken with Cupertino sliver navigation bar

main.dart

import 'package:flutter/cupertino.dart';

void main() {
  runApp(
    CupertinoApp(
      home: CupertinoPageScaffold(
        child: CustomScrollView(
          slivers: [
            CupertinoSliverNavigationBar(
              largeTitle: Text('My app'),
            ),
            SliverToBoxAdapter(
              child: Builder(
                builder: (context) {
                  return CupertinoButton(
                    child: Text('Open sheet'),
                    onPressed: () {
                      showCupertinoSheet(context: context, pageBuilder: (context) {
                        return CupertinoPageScaffold(
                          navigationBar: CupertinoNavigationBar(),
                          child: Center(child: Text('My sheet')),
                        );
                      });
                    },
                  );
                },
              ),
            ),
          ]
        ),
      ),
    ),
  );
}