CI - GSI - MOI - Panic in TestStoreDiskShutdown test

http://ci2i-unstable.northscale.in/gsi-memdb-14.05.2018-08.58.fail.html

— FAIL: TestStoreDiskShutdown (1.99s)
panic: sync: WaitGroup is reused before previous Wait has returned [recovered]
panic: sync: WaitGroup is reused before previous Wait has returned

goroutine 292 [running]:
panic(0x55c929afd9e0, 0xc42013bb00)
/home/buildbot/.cbdepscache/exploded/x86_64/go-1.7.6/go/src/runtime/panic.go:500 +0x1a1 fp=0xc4202ef968 sp=0xc4202ef8d8
testing.tRunner.func1(0xc4201740c0)
/home/buildbot/.cbdepscache/exploded/x86_64/go-1.7.6/go/src/testing/testing.go:579 +0x25d fp=0xc4202ef9e8 sp=0xc4202ef968
runtime.call32(0x0, 0x55c929c3fcf8, 0xc4201600b0, 0x800000008)
/home/buildbot/.cbdepscache/exploded/x86_64/go-1.7.6/go/src/runtime/asm_amd64.s:479 +0x4c fp=0xc4202efa18 sp=0xc4202ef9e8
panic(0x55c929afd9e0, 0xc42013bb00)
/home/buildbot/.cbdepscache/exploded/x86_64/go-1.7.6/go/src/runtime/panic.go:458 +0x243 fp=0xc4202efaa8 sp=0xc4202efa18
sync.(*WaitGroup).Wait(0xc42012421c)
/home/buildbot/.cbdepscache/exploded/x86_64/go-1.7.6/go/src/sync/waitgroup.go:133 +0xfe fp=0xc4202efaf8 sp=0xc4202efaa8
github.com/couchbase/indexing/secondary/memdb.(*MemDB).Close(0xc4201241c0)
/opt/build/goproj/src/github.com/couchbase/indexing/secondary/memdb/memdb.go:431 +0x422 fp=0xc4202efe38 sp=0xc4202efaf8
github.com/couchbase/indexing/secondary/memdb.TestStoreDiskShutdown(0xc4201740c0)
/opt/build/goproj/src/github.com/couchbase/indexing/secondary/memdb/memdb_test.go:294 +0x43c fp=0xc4202eff68 sp=0xc4202efe38
testing.tRunner(0xc4201740c0, 0x55c929c3e9d0)
/home/buildbot/.cbdepscache/exploded/x86_64/go-1.7.6/go/src/testing/testing.go:610 +0x81 fp=0xc4202eff90 sp=0xc4202eff68
runtime.goexit()
/home/buildbot/.cbdepscache/exploded/x86_64/go-1.7.6/go/src/runtime/asm_amd64.s:2086 +0x1 fp=0xc4202eff98 sp=0xc4202eff90
created by testing.(*T).Run
/home/buildbot/.cbdepscache/exploded/x86_64/go-1.7.6/go/src/testing/testing.go:646 +0x2ec