db.stats() does not show indexes or indexSize correctly for WT

> db.stats(1024*1024*1024)

{

	"db" : "ycsb",

	"collections" : 1,

	"objects" : 29799900,

	"avgObjSize" : 150.8795339917248,

	"dataSize" : 4.187407926656306,

	"storageSize" : 7.79156494140625,

	"numExtents" : 0,

	"indexes" : 1,

	"indexSize" : 0.6202392578125,

	"ok" : 1

}

> db.usertable.stats()

{

	"ns" : "ycsb.usertable",

	"count" : 29799900,

	"size" : 4496195025,

	"avgObjSize" : 150,

	"storageSize" : 8366129152,

	"capped" : false,

	"wiredTiger" : {

    [ ... ]

	},

	"totalIndexSize" : 665976832,

	"indexSizes" : {

		"_id_" : 665976832

	},

	"ok" : 1

}