panic: runtime error: slice bounds out of range

goroutine 56262544 [running]:
github.com/dgraph-io/dgraph/bp128.(*BPackIterator).Init(0xc04a9956d8, 0xc0964dd000, 0x4578, 0x4578, 0x0)
        /ext-go/1/src/github.com/dgraph-io/dgraph/bp128/bp128.go:226 +0x3cc
github.com/dgraph-io/dgraph/posting.(*PIterator).Init(0xc04a9956b0, 0xc074672eb0, 0x0)
        /ext-go/1/src/github.com/dgraph-io/dgraph/posting/list.go:101 +0xb1
github.com/dgraph-io/dgraph/posting.(*List).iterate(0xc0ccbdec80, 0x8a28a2, 0x0, 0xc04a9957d0, 0x9, 0xf)
        /ext-go/1/src/github.com/dgraph-io/dgraph/posting/list.go:558 +0xfe
github.com/dgraph-io/dgraph/posting.(*List).Postings(0xc0ccbdec80, 0x8a28a2, 0x0, 0x0, 0xc04a995940, 0x0, 0x0)
        /ext-go/1/src/github.com/dgraph-io/dgraph/posting/list.go:871 +0xa8
github.com/dgraph-io/dgraph/worker.handleUidPostings(0xf5dd60, 0xc0a1d9af60, 0xc0698ca460, 0x1, 0xc06df90420, 0xc084dc7050, 0x8a28a2, 0x0, 0x0, 0xd23ee0, ...)
        /ext-go/1/src/github.com/dgraph-io/dgraph/worker/task.go:512 +0x5d3
github.com/dgraph-io/dgraph/worker.helpProcessTask(0xf5dd60, 0xc0a1d9af60, 0xc0698ca460, 0x1, 0x0, 0x0, 0xc0a21bbac8)
        /ext-go/1/src/github.com/dgraph-io/dgraph/worker/task.go:672 +0x68b
github.com/dgraph-io/dgraph/worker.processTask(0xf5dd60, 0xc0a1d9af60, 0xc0698ca460, 0x1, 0xe43000, 0xc0a21bbb01, 0xc0698ca460)
        /ext-go/1/src/github.com/dgraph-io/dgraph/worker/task.go:613 +0x10a
github.com/dgraph-io/dgraph/worker.ProcessTaskOverNetwork(0xf5dd60, 0xc0a1d9af60, 0xc0698ca460, 0x0, 0xc0c6558300, 0x281aff)
        /ext-go/1/src/github.com/dgraph-io/dgraph/worker/task.go:141 +0x4f9
github.com/dgraph-io/dgraph/query.ProcessGraph(0xf5dd60, 0xc0a1d9af60, 0xc08cd3c580, 0xc08cd3c2c0, 0xc0b059cea0)
        /ext-go/1/src/github.com/dgraph-io/dgraph/query/query.go:1879 +0x1969
created by github.com/dgraph-io/dgraph/query.ProcessGraph
        /ext-go/1/src/github.com/dgraph-io/dgraph/query/query.go:2076 +0x10ce