assert in distinct when query is on _id

> db.test.find()

{ "_id" : BinData(3,"lL0HDD2KQEyLp3G2b83RHQ=="), "i" : 0 }

> db.test.distinct('i')

[ 0 ]

> _id = db.test.findOne()['_id']

BinData(3,"lL0HDD2KQEyLp3G2b83RHQ==")

> 

> db.test.distinct('i', {'_id': _id})

2014-01-10T15:20:05.068-0800 distinct failed: {

	"errmsg" : "exception: assertion src/mongo/db/query/type_explain.cpp:484",

	"code" : 0,

	"ok" : 0

} at src/mongo/shell/collection.js:987

2014-01-10T15:20:05.062-0800 [conn2291] test.test Assertion failure _isNSet src/mongo/db/query/type_explain.cpp 484

2014-01-10T15:20:05.068-0800 [conn2291] test.test 0xdf66d3 0xdb2940 0xd9c4cc 0xbbbab4 0x957f0d 0x9cfef9 0x9d0bdd 0x9d124a 0xb94407 0xa9c681 0x86dccb 0xdbf34c 0x7f773dd94f3a 0x7f773ca63dad 

 ./mongod(_ZN5mongo15printStackTraceERSo+0x23) [0xdf66d3]

 ./mongod(_ZN5mongo10logContextEPKc+0x190) [0xdb2940]

 ./mongod(_ZN5mongo12verifyFailedEPKcS1_j+0xec) [0xd9c4cc]

 ./mongod() [0xbbbab4]

 ./mongod(_ZN5mongo15DistinctCommand3runERKSsRNS_7BSONObjEiRSsRNS_14BSONObjBuilderEb+0x13dd) [0x957f0d]

 ./mongod(_ZN5mongo12_execCommandEPNS_7CommandERKSsRNS_7BSONObjEiRSsRNS_14BSONObjBuilderEb+0x39) [0x9cfef9]

 ./mongod(_ZN5mongo7Command11execCommandEPS0_RNS_6ClientEiPKcRNS_7BSONObjERNS_14BSONObjBuilderEb+0x8fd) [0x9d0bdd]

 ./mongod(_ZN5mongo12_runCommandsEPKcRNS_7BSONObjERNS_11_BufBuilderINS_16TrivialAllocatorEEERNS_14BSONObjBuilderEbi+0x23a) [0x9d124a]

 ./mongod(_ZN5mongo11newRunQueryERNS_7MessageERNS_12QueryMessageERNS_5CurOpES1_+0x177) [0xb94407]

 ./mongod(_ZN5mongo16assembleResponseERNS_7MessageERNS_10DbResponseERKNS_11HostAndPortE+0x751) [0xa9c681]

 ./mongod(_ZN5mongo16MyMessageHandler7processERNS_7MessageEPNS_21AbstractMessagingPortEPNS_9LastErrorE+0x8b) [0x86dccb]

 ./mongod(_ZN5mongo17PortMessageServer17handleIncomingMsgEPv+0x33c) [0xdbf34c]

 /lib64/libpthread.so.0(+0x8f3a) [0x7f773dd94f3a]

 /lib64/libc.so.6(clone+0x6d) [0x7f773ca63dad]