public HostSpec removeHost(String hostname) {
            for (Iterator<HostSpec> i = allHosts.iterator(); i.hasNext();) {
                HostSpec host = i.next();
                if (host.hostname().equals(hostname)) {
                    i.remove();
                    return host;
                }
            }
            return null;
        }
Returns a host by cluster name and index, or null if there is no host with the given values in this
node-repository/src/test/java/com/yahoo/vespa/hosted/provision/provisioning/ProvisioningTest.java