panic on updater

See panic when running the following sanity test locally. Full log attached.

./testrunner -i local.ini  -t xdcr.filterXDCR.XDCRFilterTests.test_xdcr_with_filter,items=5000,pause=C1:C2,rdirection=unidirection,ctopology=chain,replication_type=xmem,default@C1=filter_expression:C11,default@C1=filter_expression:C21,checkpoint_interval=60

2017-06-07T13:48:13.521-07:00 INFO GOXDCR.PipelineMgr: Stopping pipeline 2d30603f86643e1b12d7ccb7060f7866/default/default since the replication spec has been deleted
panic: Updater obj nil when replicationStatus exists

goroutine 43287 [running]:
panic(0x14f39c0, 0xc42039f370)
        /Users/yu/.cbdepscache/exploded/x86_64/go-1.8.1/go/src/runtime/panic.go:531 +0x1cf fp=0xc421372ec0 sp=0xc421372e28
github.com/couchbase/goxdcr/pipeline_manager.(*PipelineManager).RemoveReplicationStatus(0xc4200b5130, 0xc420292831, 0x30, 0x0, 0x0)
        /Users/yu/m2/goproj/src/github.com/couchbase/goxdcr/pipeline_manager/pipeline_manager.go:187 +0x244 fp=0xc421372f48 sp=0xc421372ec0
github.com/couchbase/goxdcr/replication_manager.onDeleteReplication(0xc420292831, 0x30, 0xc420019d30, 0x1, 0x0)
        /Users/yu/m2/goproj/src/github.com/couchbase/goxdcr/replication_manager/metakv_change_listener.go:421 +0x45 fp=0xc421372fb8 sp=0xc421372f48
runtime.goexit()
        /Users/yu/.cbdepscache/exploded/x86_64/go-1.8.1/go/src/runtime/asm_amd64.s:2197 +0x1 fp=0xc421372fc0 sp=0xc421372fb8
created by github.com/couchbase/goxdcr/replication_manager.(*ReplicationSpecChangeListener).replicationSpecChangeHandlerCallback
        /Users/yu/m2/goproj/src/github.com/couchbase/goxdcr/replication_manager/metakv_change_listener.go:166 +0x937