Error when I use sparkContext.makeRDD(Seq())

when i use sc.makeRDD below
```
val data3 = sc.makeRDD(Seq())
println(data3.partitions.length)
```
I got an error:
Exception in thread "main" java.lang.IllegalArgumentException: Positive number of slices required
We can fix this bug just modify the last line ,do a check of seq.size
````
def makeRDD[T: ClassTag](seq: Seq[(T, Seq[String])]): RDD[T] = withScope

{ assertNotStopped() val indexToPrefs = seq.zipWithIndex.map(t => (t._2, t._1._2)).toMap new ParallelCollectionRDD[T](this, seq.map(_._1), seq.size, indexToPrefs) }

```