Unit Test Failure: remoteRelationsSuite.TestRemoteDyingRelationsChangedError

I've seen this twice in two days:

As per: http://ci.jujucharms.com/job/make-check-juju/1220/testReport/junit/github/com_juju_juju_worker_remoterelations/TestPackage/

[LOG] 0:00.201 DEBUG juju.worker.remoterelations local relation units changed -> publishing: params.RemoteRelationChangeEvent{RelationToken:"token-db2:db django:db", ApplicationToken:"token-django", Life:"", ForceCleanup:(*bool)(nil), Suspended:(*bool)(nil), SuspendedReason:"", ChangedUnits:[]params.RemoteRelationUnitChange(nil), DepartedUnits:[]int{1}, Macaroons:macaroon.Slice{(*macaroon.Macaroon)(0xc0001c0460)}}
[LOG] 0:00.201 ERROR juju.worker.remoterelations error in remote application worker for db2: publishing relation change {RelationToken:token-db2:db django:db ApplicationToken:token-django Life: ForceCleanup:<nil> Suspended:<nil> SuspendedReason: ChangedUnits:[] DepartedUnits:[1] Macaroons:[0xc0001c0460]} to remote model remote-model-uuid: failed
[LOG] 0:00.302 DEBUG juju.worker.remoterelations remote controller api addresses: [1.2.3.4:1234]
[LOG] 0:00.352 DEBUG juju.worker.remoterelations relations changed: []string{"db2:db django:db"}, true
[LOG] 0:00.352 DEBUG juju.worker.remoterelations relation "db2:db django:db" changed: {Error:<nil> Result:0xc000115550}
[LOG] 0:00.352 DEBUG juju.worker.remoterelations register remote relation db2:db django:db
[LOG] 0:00.352 DEBUG juju.worker.remoterelations import remote application token token-offer-db2-uuid for db2
remoterelations_test.go:498:
    s.assertRemoteRelationsChangedError(c, true)
remoterelations_test.go:73:
    c.Fatalf("failed to see expected calls. saw: %v", calls)
... Error: failed to see expected calls. saw: [{Relations [[db2:db django:db]]} {ExportEntities [[application-django relation-db2.db#django.db]]} {RegisterRemoteRelations [[{token-django model-local-model-uuid token-db2:db django:db {db2 requires db2 0} { map[] []} offer-db2-uuid data [0xc0001a7e30]}]]} {SaveMacaroon [relation-db2.db#django.db 0xc0001c04d0]} {ImportRemoteEntity [application-db2 token-offer-db2-uuid]} {WatchRelationSuspendedStatus [token-db2:db django:db [0xc0001c04d0]]} {WatchLocalRelationUnits [db2:db django:db]} {WatchRelationUnits [token-db2:db django:db [0xc0001c04d0]]}]