java.lang.IllegalStateException: la actividad ha sido destruida

Sé que hay varias preguntas similares.

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

            //...

            getSupportFragmentManager().beginTransaction().add(R.id.fragment_container, new LoginFragment()).commit();
        }

        @Override
        protected void onSaveInstanceState(Bundle outState) {
            super.onSaveInstanceState(outState);

            Log.i(TAG, "DZActivity onSaveInstanceState");
        }

        @Override
        public void onRequestStarted() {

            DZActivity.this.runOnUiThread(new Runnable() {

                @Override
                public void run() {

                    Log.i(TAG, "DZActivity onRequestStarted");

                    getSupportFragmentManager().beginTransaction().replace(R.id.fragment_container, new ProgressFragment()).commit();
                }
            });
        }

        @Override
        public void onSignIn(String accessToken) {

            DZActivity.this.runOnUiThread(new Runnable() {

                @Override
                public void run() {

                    Log.i(TAG, "DZActivity onSignIn");

                    getSupportFragmentManager().beginTransaction().replace(R.id.fragment_container, new HomeFragment()).commit();
                }
            });
        }

Después de presionar Atrás, inicio mi aplicación por segunda vez y después de presionar "Iniciar sesión" obtengo:

08-07 18:02:54.609: I/DZActivity(3302): DZActivity onCreate
08-07 18:02:54.659: I/DZActivity(3302): DZActivity onResume
08-07 18:03:05.349: I/DZActivity(3302): DZActivity onRequestStarted
08-07 18:03:07.929: I/DZActivity(3302): DZActivity onSignIn
08-07 18:03:19.489: I/DZActivity(3302): DZActivity onPause
08-07 18:03:19.769: I/DZActivity(3302): DZActivity onStop
08-07 18:03:19.769: I/DZActivity(3302): DZActivity onDestroy
08-07 18:03:42.799: I/DZActivity(3302): DZActivity onCreate
08-07 18:03:42.819: I/DZActivity(3302): DZActivity onResume
08-07 18:03:49.559: I/DZActivity(3302): DZActivity onRequestStarted
08-07 18:03:49.559: E/AndroidRuntime(3302): java.lang.IllegalStateException: Activity has been destroyed
08-07 18:03:49.559: E/AndroidRuntime(3302):     at android.support.v4.app.FragmentManagerImpl.enqueueAction(FragmentManager.java:1376)
08-07 18:03:49.559: E/AndroidRuntime(3302):     at android.support.v4.app.BackStackRecord.commitInternal(BackStackRecord.java:595)
08-07 18:03:49.559: E/AndroidRuntime(3302):     at android.support.v4.app.BackStackRecord.commitAllowingStateLoss(BackStackRecord.java:578)

¿Por qué lo obtengo si mi actividad se recreó e incluso no se llamó a onSaveInstanceState?

Respuestas a la pregunta(1)

Su respuesta a la pregunta