Still error in Unity 5.6.4f1-64bit
But you can use like that:

public class Test : MonoBehaviour {

Coroutine coroutine;
// Use this for initialization
void Start () {
coroutine = StartCoroutine(Coroutine_1());
}

private IEnumerator Coroutine_1()
{
yield return new WaitForEndOfFrame();
StopCoroutine(coroutine);
yield return new WaitForEndOfFrame();
Debug.Log("Test");
}
}

Error still persist in Unity 5.4.3

Error in Unity 5.3.4f1
public void StartInstantiate(){
StopInstantiate ();
coroutine = IEInstantiate ();
StartCoroutine (coroutine);
}

private void StopInstantiate(){
if (coroutine != null)
StopCoroutine (coroutine);
coroutine = null;
}

How is this bug back now... It needs to be fixed again! How to reopen it? My project is just too big to submit a bug report.

Still in 5.3 and 5.4

same with 5.3.4 too...

5.3.1.f1 Coroutine continue failure
StopCourutine(Courutine)

I have it too. Also with IEnumerator !

Same problem in Unity 5.3.1f1

It's happening again (Unity 5.3.1f1)