[SERVER-8290] Multiple $slice on fixed sized array causes wrong/duplicate elements - MongoDB

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Steps To Reproduce:

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db.fs.update(
{x:4}
,{ $push : { y : { $each : [
{a:5}
,
{a:1}
,
{a:4}
,
{a:2}
,
{a:3}
], $slice:-4, $slice:-3, $sort:
{a:1}
} } })

db.fs.find()
{ "_id" : ObjectId("50fd0989a8f4e3eef998f845"), "x" : 4, "y" : [
{ "a" : 4 }
,
{ "a" : 4 }
,
{ "a" : 5 }
] }

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db.fs.update( {x:4} ,{ $push : { y : { $each : [ {a:5} , {a:1} , {a:4} , {a:2} , {a:3} ], $slice:-4, $slice:-3, $sort: {a:1} } } }) db.fs.find() { "_id" : ObjectId("50fd0989a8f4e3eef998f845"), "x" : 4, "y" : [ { "a" : 4 } , { "a" : 4 } , { "a" : 5 } ] }

Doing a $push with multiple $slice for fixed sized arrays causes wrong/duplicate elements.