OnApplicationPause is not working correctly in Unity 5.

I upgraded my project from unity 4.5 to unity 5.0.
And i am experiencing the abnormal behavior of OnApplicationPause method of unity.
I have the following code.

void OnApplicationPause (bool pauseStatus)
	{
		if (pauseStatus)
		   print ("Application Paused");
		else
		   print ("Application Resume");
	}

It never print Application Paused when I switch out from unity editor but it print Application Resume when i switch back to unity editor. this works fine in Unity 4.5.

Looks to me like it could be the fixed issue discovered in version 5.1.xxx

Maybe you upgrade to a higher or stay on Unity 4.5 if you need lower versions because of maintaining your projects.