coalescing RDD into equally sized partitions

[Walrus theCat]

Hi,

sc.parallelize(Array.tabulate(100)(i=>i)).filter( _ % 20 == 0
).coalesce(5,true).glom.collect  yields

Array[Array[Int]] = Array(Array(0, 20, 40, 60, 80), Array(), Array(),
Array(), Array())

How do I get something more like:

 Array(Array(0), Array(20), Array(40), Array(60), Array(80))

Thanks