Panic during index scan for large index keys (entryCache.Update)

panic: runtime error: slice bounds out of range [recovered]
panic: runtime error: slice bounds out of range

goroutine 19465 [running]:
panic(0xe3c3e0, 0xc4200160d0)
/home/couchbase/.cbdepscache/exploded/x86_64/go-1.7.6/go/src/runtime/panic.go:500 +0x1a1 fp=0xc4dfae30f0 sp=0xc4dfae3060
github.com/couchbase/indexing/secondary/indexer.(*IndexScanSource).Routine.func1(0xc44292fe30)
goproj/src/github.com/couchbase/indexing/secondary/indexer/scan_pipeline.go:133 +0xcf fp=0xc4dfae3148 sp=0xc4dfae30f0
runtime.call32(0x0, 0x10676b8, 0xc425357e30, 0x800000008)
/home/couchbase/.cbdepscache/exploded/x86_64/go-1.7.6/go/src/runtime/asm_amd64.s:479 +0x4c fp=0xc4dfae3178 sp=0xc4dfae3148
panic(0xe3c3e0, 0xc4200160d0)
/home/couchbase/.cbdepscache/exploded/x86_64/go-1.7.6/go/src/runtime/panic.go:458 +0x243 fp=0xc4dfae3208 sp=0xc4dfae3178
runtime.panicslice()
/home/couchbase/.cbdepscache/exploded/x86_64/go-1.7.6/go/src/runtime/panic.go:34 +0x6d fp=0xc4dfae3238 sp=0xc4dfae3208
github.com/couchbase/indexing/secondary/indexer.(*entryCache).Update(0xc54e4a4e00, 0x7f21f2f3434c, 0x53, 0x53, 0xc54e4fab40, 0x4, 0x4, 0xc54d5edbc0, 0x4, 0x4)
goproj/src/github.com/couchbase/indexing/secondary/indexer/scan_pipeline.go:1333 +0x1dd fp=0xc4dfae32d8 sp=0xc4dfae3238
github.com/couchbase/indexing/secondary/indexer.filterScanRow2(0x7f21f2f3434c, 0x53, 0x53, 0x1839580, 0xc54f714f00, 0x1839580, 0xc54f714f40, 0x3, 0xf8fd99, 0xb, ...)
goproj/src/github.com/couchbase/indexing/secondary/indexer/scan_pipeline.go:588 +0x40f fp=0xc4dfae34b8 sp=0xc4dfae32d8
github.com/couchbase/indexing/secondary/indexer.(*IndexScanSource).Routine.func3(0x7f21f2f3434c, 0x53, 0x53, 0x53, 0x0)
goproj/src/github.com/couchbase/indexing/secondary/indexer/scan_pipeline.go:221 +0x1214 fp=0xc4dfae3720 sp=0xc4dfae34b8
github.com/couchbase/indexing/secondary/indexer.scanSingleSlice.func2(0x7f21f2f3434c, 0x53, 0x53, 0xc54f74e560, 0x0)
goproj/src/github.com/couchbase/indexing/secondary/indexer/scan_scatter.go:196 +0x16e fp=0xc4dfae37a8 sp=0xc4dfae3720
github.com/couchbase/indexing/secondary/indexer.(*memdbSnapshot).iterEqualKeys(0xc534e86f00, 0x1839580, 0xc54f714f40, 0xc54f65f560, 0x1067e88, 0xc54f65f500, 0x416f3e, 0xc54f65f500)
goproj/src/github.com/couchbase/indexing/secondary/indexer/memdb_slice_impl.go:1630 +0x1ae fp=0xc4dfae3830 sp=0xc4dfae37a8
github.com/couchbase/indexing/secondary/indexer.(*memdbSnapshot).Iterate(0xc534e86f00, 0x18354e0, 0xc54f630de0, 0x1839580, 0xc54f714f00, 0x1839580, 0xc54f714f40, 0x3, 0x1067e88, 0xc54f65f500, ...)
goproj/src/github.com/couchbase/indexing/secondary/indexer/memdb_slice_impl.go:1596 +0x3d9 fp=0xc4dfae38c8 sp=0xc4dfae3830
github.com/couchbase/indexing/secondary/indexer.(*memdbSnapshot).Range(0xc534e86f00, 0x18354e0, 0xc54f630de0, 0x1839580, 0xc54f714f00, 0x1839580, 0xc54f714f40, 0x3, 0xc54f65f500, 0x1, ...)
goproj/src/github.com/couchbase/indexing/secondary/indexer/memdb_slice_impl.go:1546 +0xb2 fp=0xc4dfae3938 sp=0xc4dfae38c8
github.com/couchbase/indexing/secondary/indexer.scanSingleSlice(0xc54c91cd80, 0x1839580, 0xc54f714f00, 0x1839580, 0xc54f714f40, 0x3, 0xf8fd99, 0xb, 0xc54f70be50, 0x1, ...)
goproj/src/github.com/couchbase/indexing/secondary/indexer/scan_scatter.go:206 +0x41b fp=0xc4dfae3a00 sp=0xc4dfae3938
github.com/couchbase/indexing/secondary/indexer.scanOne(0xc54c91cd80, 0x1839580, 0xc54f714f00, 0x1839580, 0xc54f714f40, 0x3, 0xf8fd99, 0xb, 0xc54f70be50, 0x1, ...)
goproj/src/github.com/couchbase/indexing/secondary/indexer/scan_scatter.go:148 +0x11e fp=0xc4dfae3b18 sp=0xc4dfae3a00
github.com/couchbase/indexing/secondary/indexer.scatter(0xc54c91cd80, 0x1839580, 0xc54f714f00, 0x1839580, 0xc54f714f40, 0x3, 0xf8fd99, 0xb, 0xc54f70be50, 0x1, ...)
goproj/src/github.com/couchbase/indexing/secondary/indexer/scan_scatter.go:55 +0xc6 fp=0xc4dfae3bc8 sp=0xc4dfae3b18
github.com/couchbase/indexing/secondary/indexer.(*IndexScanSource).Routine(0xc44292fe30, 0x0, 0x0)
goproj/src/github.com/couchbase/indexing/secondary/indexer/scan_pipeline.go:336 +0x810 fp=0xc4dfae3f18 sp=0xc4dfae3bc8
github.com/couchbase/indexing/secondary/pipeline.(*Pipeline).runIt.func1(0xc54f74e480, 0xc54f74af30)
goproj/src/github.com/couchbase/indexing/secondary/pipeline/pipeline.go:75 +0x45 fp=0xc4dfae3f80 sp=0xc4dfae3f18
runtime.goexit()
/home/couchbase/.cbdepscache/exploded/x86_64/go-1.7.6/go/src/runtime/asm_amd64.s:2086 +0x1 fp=0xc4dfae3f88 sp=0xc4dfae3f80
created by github.com/couchbase/indexing/secondary/pipeline.(*Pipeline).runIt
goproj/src/github.com/couchbase/indexing/secondary/pipeline/pipeline.go:80 +0x66