bad map state goxdcr/pipeline_svc.(*checkpointMgrCollector).OnEvent.

From 4.0.0 build 2213 Windows

fatal error: bad map state

goroutine 59038 [running]:
runtime.gothrow(0x9dd850, 0xd)
c:/go/src/runtime/panic.go:503 +0x8e fp=0xc08256b770 sp=0xc08256b758
runtime.evacuate(0x82dec0, 0xc082908810, 0x13)
c:/go/src/runtime/hashmap.go:799 +0x371 fp=0xc08256b830 sp=0xc08256b770
runtime.growWork(0x82dec0, 0xc082908810, 0x72)
c:/go/src/runtime/hashmap.go:769 +0x91 fp=0xc08256b850 sp=0xc08256b830
runtime.mapassign1(0x82dec0, 0xc082908810, 0xc08256b946, 0xc08256b9b8)
c:/go/src/runtime/hashmap.go:408 +0x196 fp=0xc08256b8f0 sp=0xc08256b850
github.com/couchbase/goxdcr/pipeline_svc.(*checkpointMgrCollector).OnEvent(0xc0823e4020, 0x6, 0x954f80, 0xc0826c4880, 0x19e0a8, 0xc08236f680, 0x0, 0x0, 0x0, 0xc082b102a0)
C:/Jenkins/workspace/sherlock-windows/couchbase/goproj/src/github.com/couchbase/goxdcr/pipeline_svc/statistics_manager.go:938 +0x257 fp=0xc08256b9f0 sp=0xc08256b8f0
github.com/couchbase/goxdcr/component.(*AbstractComponent).RaiseEvent(0xc083787520, 0x6, 0x954f80, 0xc0826c4880, 0x19e0a8, 0xc08236f680, 0x0, 0x0, 0x0, 0xc082b102a0)
C:/Jenkins/workspace/sherlock-windows/couchbase/goproj/src/github.com/couchbase/goxdcr/component/abstract_component.go:84 +0x2f3 fp=0xc08256bb10 sp=0xc08256b9f0
github.com/couchbase/goxdcr/pipeline_svc.(*CheckpointManager).raiseSuccessCkptForVbEvent(0xc08236f680, 0xf8ce29e91041, 0x5d, 0x0, 0x0, 0x1128690, 0xc08267ab68, 0x5d, 0x3aa)
C:/Jenkins/workspace/sherlock-windows/couchbase/goproj/src/github.com/couchbase/goxdcr/pipeline_svc/checkpoint_manager.go:721 +0x1b1 fp=0xc08256bbf0 sp=0xc08256bb10
github.com/couchbase/goxdcr/pipeline_svc.(*CheckpointManager).do_checkpoint(0xc08236f680, 0x314e03aa, 0x0, 0x0)
C:/Jenkins/workspace/sherlock-windows/couchbase/goproj/src/github.com/couchbase/goxdcr/pipeline_svc/checkpoint_manager.go:705 +0x774 fp=0xc08256bd00 sp=0xc08256bbf0
github.com/couchbase/goxdcr/pipeline_svc.(*CheckpointManager).performCkpt(0xc08236f680, 0xc082aa2fc0, 0xc082246d80)
C:/Jenkins/workspace/sherlock-windows/couchbase/goproj/src/github.com/couchbase/goxdcr/pipeline_svc/checkpoint_manager.go:652 +0x5ec fp=0xc08256bfc8 sp=0xc08256bd00
runtime.goexit()
c:/go/src/runtime/asm_amd64.s:2232 +0x1 fp=0xc08256bfd0 sp=0xc08256bfc8
created by github.com/couchbase/goxdcr/pipeline_svc.(*CheckpointManager).checkpointing
C:/Jenkins/workspace/sherlock-windows/couchbase/goproj/src/github.com/couchbase/goxdcr/pipeline_svc/checkpoint_manager.go:610 +0x3c9