tolerates Consul providing duplicate keys

[jhovell]

@rickfast here you go

reference:

#96

[gjesse]

Is there a more specific service key we should be using? does this method mean that some entities that should be included in the map aren't? Like maybe the key should be a combo of host/port/protocol instead of host/port - i don't like that this is just throwing away potential duplicates.

[jhovell]

@gjesse you're definitely right. I think in the case of services some unique hash of the tags should be included as well. I don't know Consul well enough to say for sure & guessing the fix might be more involved, as I didn't look at all the places where this immutable map key is used. For key/value store, I think this would never happen, it's just good defensive coding.

this is at least an improvement, now we throw away 'duplicate' services instead of crashing ...