After dropping a shard and restarting server panics

[pauldix]

Stacktrace:

[2014/02/27 11:17:50 UTC] [INFO] (coordinator.(*RaftServer).raftEventHandler:394) (raft:7f9daa9) Selected as leader. Starting leader loop.
panic: runtime error: invalid memory address or nil pointer dereference
[signal 0xb code=0x1 addr=0xb0 pc=0x55ecea]

goroutine 15 [running]:
runtime.panic(0x87d020, 0xff21a8)
    /home/vagrant/bin/go/src/pkg/runtime/panic.c:266 +0xb6
cluster.(*ClusterConfiguration).updateOrRemoveShard(0xc2100d5000, 0x2, 0xc21016a390, 0x2, 0x4)
    /home/vagrant/influxdb/src/cluster/cluster_configuration.go:973 +0xaa
cluster.(*ClusterConfiguration).DropShard(0xc2100d5000, 0x2, 0xc21016a390, 0x2, 0x4, ...)
    /home/vagrant/influxdb/src/cluster/cluster_configuration.go:903 +0x52
coordinator.(*DropShardCommand).Apply(0xc210143da0, 0x7f1537edc290, 0xc210050000, 0x7f1537ee2390, 0xc210143da0, ...)
    /home/vagrant/influxdb/src/coordinator/command.go:268 +0x7b
github.com/goraft/raft.func·005(0xc210085600, 0x7f1537ed9678, 0xc210143da0, 0x20, 0x20, ...)
    /home/vagrant/influxdb/src/github.com/goraft/raft/server.go:195 +0x364
github.com/goraft/raft.(*Log).setCommitIndex(0xc210073a10, 0x21, 0x0, 0x0)
    /home/vagrant/influxdb/src/github.com/goraft/raft/log.go:371 +0x36e
github.com/goraft/raft.(*server).processAppendEntriesResponse(0xc210050000, 0xc2100bcb00)
    /home/vagrant/influxdb/src/github.com/goraft/raft/server.go:948 +0x4b2
github.com/goraft/raft.(*server).leaderLoop(0xc210050000)
    /home/vagrant/influxdb/src/github.com/goraft/raft/server.go:775 +0x4d0
github.com/goraft/raft.(*server).loop(0xc210050000)
    /home/vagrant/influxdb/src/github.com/goraft/raft/server.go:560 +0x33f
created by github.com/goraft/raft.(*server).Start
    /home/vagrant/influxdb/src/github.com/goraft/raft/server.go:465 +0x7af