corrupted ipns entry in local cache

I was able to break my local ipns publishing:

```
➜ ~ ipfs name publish
Error: proto: required field "{Unknown}" not set
```

I did this by first publishing an entry normally, then:

```
ipfs dht get /ipns/ > ipns-data
cat ipns-data | ipfs dht put /ipns/
```

Something must not be quite right here in the round tripping of the record.

This also appears to make it impossible for me to publish new ipns values for the time being.