Bug: onNewIntent not called for singleTop activity with Intent.FLAG_ACTIVITY_NEW_TASK

Question

There appears to be a bug in startActivity.

By setting activities to be singleTop with different taskAffinity in AndroidManifest.xml and using the Intent.FLAG_ACTIVITY_NEW_TASK when calling startActivity, two activities can be created in two tasks (one activity per task).

Calling startActivity again will return to the first activity/task and onNewIntent is called. However, calling startActivity a forth time will return to the second activity/task, but onNewIntent is not called.

The only difference between the two tasks is their taskAffinity. Somehow, asymmetrical behaviour is observed.

However, if the Intent.FLAG_ACTIVITY_SINGLE_TOP is also used, then onNewIntent is called as expected.

It would appear that singleTop in AndroidManifest.xml is not the same as Intent.FLAG_ACTIVITY_SINGLE_TOP in the Intent.

public class ActivityA extends Activity implements OnClickListener {
    private String tag;

    @Override
    public void onCreate(final Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        tag = getClass().getName();
        Log.v(tag, "onCreate()");

        setContentView(R.layout.main);
        Button button = (Button)findViewById(R.id.button);
        button.setText(tag.endsWith("ActivityA") ? "Activity B"
                : "Activity A");
        button.setOnClickListener(this);
    }

    @Override
    public void onClick(View v) {
        Intent intent;
        int flags = Intent.FLAG_ACTIVITY_NEW_TASK
        // | Intent.FLAG_ACTIVITY_SINGLE_TOP
        ;

        Log.v(tag, "onClick()");

        intent = new Intent(this,
                tag.endsWith("ActivityA") ? ActivityB.class
                        : ActivityA.class);
        intent.setFlags(flags);
        startActivity(intent);
    }

    @Override
    protected void onNewIntent(Intent intent) {
        Log.v(tag, "onNewIntent()");
    }
}

public class ActivityB extends ActivityA {

}

<?xml version="1.0" encoding="utf-8"?>
<manifest
    xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.test"
    android:versionCode="1"
    android:versionName="1.0">
    <application
        android:icon="@drawable/icon"
        android:label="@string/app_name">

        <activity
            android:name=".ActivityA"
            android:launchMode="singleTop"
            android:label="Activity A">
            <intent-filter>
                <action
                    android:name="android.intent.action.MAIN" />
                <category
                    android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

        <activity
            android:name=".ActivityB"
            android:launchMode="singleTop"
            android:label="Activity B"
            android:taskAffinity="activity.B">
        </activity>

    </application>
</manifest>