memdb panic in drop index

memdb panic in drop while running functional test TestMixedDatatypesRange_Float.

2016-03-10T15:38:23.203+05:30 [Info] Indexer::sendStreamUpdateForDropIndex Success Stream MAINT_STREAM Bucket default
panic: send on closed channel

goroutine 373200 [running]:
panic(0x48bd840, 0xc8278eb630)
/Users/deepkaran/.cbdepscache/exploded/x86_64/go-1.6/go/src/runtime/panic.go:464 +0x3e6
github.com/couchbase/indexing/secondary/memdb.(*MemDB).collectDead(0xc8296b50a0)
/Users/deepkaran/workspace/cb_watson_r/goproj/src/github.com/couchbase/indexing/secondary/memdb/memdb.go:624 +0x363
github.com/couchbase/indexing/secondary/memdb.(*MemDB).GC(0xc8296b50a0)
/Users/deepkaran/workspace/cb_watson_r/goproj/src/github.com/couchbase/indexing/secondary/memdb/memdb.go:631 +0x59
github.com/couchbase/indexing/secondary/memdb.(*Snapshot).Close(0xc828a94c20)
/Users/deepkaran/workspace/cb_watson_r/goproj/src/github.com/couchbase/indexing/secondary/memdb/memdb.go:517 +0x1eb
github.com/couchbase/indexing/secondary/memdb.(*MemDB).StoreToDisk.func1(0xc8243a0a5f, 0xc8243a0d40)
/Users/deepkaran/workspace/cb_watson_r/goproj/src/github.com/couchbase/indexing/secondary/memdb/memdb.go:782 +0x31
github.com/couchbase/indexing/secondary/memdb.(*MemDB).StoreToDisk(0xc8296b50a0, 0xc82fc33700, 0x79, 0xc828a94c20, 0x10, 0x0, 0x0, 0x0)
/Users/deepkaran/workspace/cb_watson_r/goproj/src/github.com/couchbase/indexing/secondary/memdb/memdb.go:886 +0x122a
github.com/couchbase/indexing/secondary/indexer.(*memdbSlice).doPersistSnapshot(0xc832bba000, 0xc826116d20)
/Users/deepkaran/workspace/cb_watson_r/goproj/src/github.com/couchbase/indexing/secondary/indexer/memdb_slice_impl.go:624 +0x4e4
created by github.com/couchbase/indexing/secondary/indexer.(*memdbSlice).OpenSnapshot
/Users/deepkaran/workspace/cb_watson_r/goproj/src/github.com/couchbase/indexing/secondary/indexer/memdb_slice_impl.go:591 +0x1db