worker/peergrouper: test failure

Replica sets are, well, sets, not lists. The tests should use jc.SameContent

[LOG] 0:00.003 INFO juju.worker.peergrouper successfully changed replica set to []replicaset.Member{replicaset.Member{Id:0, Address:"0.1.2.10:1234", Arbiter:(*bool)(nil), BuildIndexes:(*bool)(nil), Hidden:(*bool)(nil), Priority:(*float64)(nil), Tags:map[string]string{"juju-machine-id":"10"}, SlaveDelay:(*time.Duration)(nil), Votes:(*int)(nil)}, replicaset.Member{Id:1, Address:"0.1.2.11:1234", Arbiter:(*bool)(nil), BuildIndexes:(*bool)(nil), Hidden:(*bool)(nil), Priority:(*float64)(0xc2084af3b8), Tags:map[string]string{"juju-machine-id":"11"}, SlaveDelay:(*time.Duration)(nil), Votes:(*int)(0xc2084af3b0)}, replicaset.Member{Id:2, Address:"0.1.2.12:1234", Arbiter:(*bool)(nil), BuildIndexes:(*bool)(nil), Hidden:(*bool)(nil), Priority:(*float64)(0xc2084af3e0), Tags:map[string]string{"juju-machine-id":"12"}, SlaveDelay:(*time.Duration)(nil), Votes:(*int)(0xc2084af3c8)}}
worker_test.go:382:
    c.Assert(instanceIds, jc.DeepEquals, []instance.Id{"id-10", "id-11", "id-12"})
... obtained []instance.Id = []instance.Id{"id-12", "id-10", "id-11"}
... expected []instance.Id = []instance.Id{"id-10", "id-11", "id-12"}
... mismatch at [0]: unequal; obtained "id-12"; expected "id-10"

[LOG] 0:00.010 ERROR juju.worker.peergrouper peergrouper loop terminated: tomb: dying
OOPS: 9 passed, 2 FAILED
--- FAIL: TestPackage (1.14 seconds)
FAIL
FAIL launchpad.net/juju-core/worker/peergrouper 1.236s