Starting from support library version 26.0.0 Beta 1 a new API is available in FragmentManager and Fragment classes:
FragmentManager and Fragment have an isStateSaved() method to allow querying whether or not a transaction will be allowed without state loss. This is especially useful to check when handling an onClick() event before executing any transaction.
From docs of android.support.v4.app.FragmentManager#isStateSaved():
Returns true if the FragmentManager‘s state has already been saved by its host. Any operations that would change saved state should not be performed if this method returns true. For example, any popBackStack() method, such as popBackStackImmediate() or any FragmentTransaction using commit() instead of commitAllowingStateLoss() will change the state and will result in an error.
This API will ship with framework’s android.app.FragmentManager starting from Android O.