Error closing cassandra iter on read: gocql: no hosts available in the pool

[smcquay]

I noticed this in the output of a long-running event master process when I'd enable/disable the annotations in a Grafana dashboard.

The c.FindByID unbounded concurrent dispatch code looked suspicious at first glance, and the message seems incorrect.

A related issue was merged in upstream so this may be resolved when we upgrade our dependencies.

I was unable to reproduce this pathology.