title: Can not perform this action after onSaveInstanceState WHEN commit
body: <p>I have got exception when <code>ft.commit()</code> and I don't know why.</p>
  <pre><code>java.lang.IllegalStateException: Can not perform this action after onSaveInstanceState
      at android.support.v4.app.FragmentManagerImpl.checkStateLoss(FragmentManager.java:1448)
      at android.support.v4.app.FragmentManagerImpl.enqueueAction(FragmentManager.java:1466)
      at android.support.v4.app.BackStackRecord.commitInternal(BackStackRecord.java:634)
      at android.support.v4.app.BackStackRecord.commit(BackStackRecord.java:613)
      at MainActivity.attachFragment(MainActivity.java:242)
      at MainActivity.attachFragment(MainActivity.java:225)
      at MainActivity.showHome(MainActivity.java:171)
      at MainActivity.onComplete(MainActivity.java:278)
      at MDownloadManager.onDownloadComplete(MDownloadManager.java:83)
      at DownloadRequestQueue$CallBackDelivery$2.run(DownloadRequestQueue.java:61)
      at android.os.Handler.handleCallback(Handler.java:733)
      at android.os.Handler.dispatchMessage(Handler.java:95)
      at android.os.Looper.loop(Looper.java:149)
      at android.app.ActivityThread.main(ActivityThread.java:5257)
      at java.lang.reflect.Method.invokeNative(Method.java)
      at java.lang.reflect.Method.invoke(Method.java:515)
      at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:609)
      at dalvik.system.NativeStart.main(NativeStart.java)
  </code></pre>
  <p>Here is my method where crash is comming.</p>
  <pre><code>FragmentManager     fm = getSupportFragmentManager();
  FragmentTransaction ft = fm.beginTransaction();
  
  if(addToBackStack) {
      ft.addToBackStack(null);
      ft.add(R.id.frame_container, fragment, tag);
  } else {
      ft.replace(R.id.frame_container, fragment, tag);
  }
  
  ft.commit();
  </code></pre>
  <p>Have you got any idea what is wrong?</p>
  <p>I don't use <code>onSaveInstanceState</code> in my project.</p>