unconfigured-node-name fails with assertion error on windows

[alpar-t]

https://scans.gradle.com/s/rleubfn3somoa/console-log?task=:qa:unconfigured-node-name:integTestRunner#L34

» [2019-07-20T09:42:25,054][ERROR][o.e.b.ElasticsearchUncaughtExceptionHandler] [] fatal error in thread [main], exiting
--
»  java.lang.AssertionError: null
»  	at org.elasticsearch.common.util.concurrent.EsExecutors.daemonThreadFactory(EsExecutors.java:238) ~[elasticsearch-8.0.0-SNAPSHOT.jar:8.0.0-SNAPSHOT]
»  	at org.elasticsearch.cluster.service.ClusterApplierService.createThreadPoolExecutor(ClusterApplierService.java:142) ~[elasticsearch-8.0.0-SNAPSHOT.jar:8.0.0-SNAPSHOT]
»  	at org.elasticsearch.cluster.service.ClusterApplierService.doStart(ClusterApplierService.java:136) ~[elasticsearch-8.0.0-SNAPSHOT.jar:8.0.0-SNAPSHOT]
»  	at org.elasticsearch.common.component.AbstractLifecycleComponent.start(AbstractLifecycleComponent.java:59) ~[elasticsearch-8.0.0-SNAPSHOT.jar:8.0.0-SNAPSHOT]
»  	at org.elasticsearch.cluster.service.ClusterService.doStart(ClusterService.java:101) ~[elasticsearch-8.0.0-SNAPSHOT.jar:8.0.0-SNAPSHOT]
»  	at org.elasticsearch.common.component.AbstractLifecycleComponent.start(AbstractLifecycleComponent.java:59) ~[elasticsearch-8.0.0-SNAPSHOT.jar:8.0.0-SNAPSHOT]
»  	at org.elasticsearch.node.Node.start(Node.java:706) ~[elasticsearch-8.0.0-SNAPSHOT.jar:8.0.0-SNAPSHOT]
»  	at org.elasticsearch.bootstrap.Bootstrap.start(Bootstrap.java:271) ~[elasticsearch-8.0.0-SNAPSHOT.jar:8.0.0-SNAPSHOT]
»  	at org.elasticsearch.bootstrap.Bootstrap.init(Bootstrap.java:348) ~[elasticsearch-8.0.0-SNAPSHOT.jar:8.0.0-SNAPSHOT]
»  	at org.elasticsearch.bootstrap.Elasticsearch.init(Elasticsearch.java:159) ~[elasticsearch-8.0.0-SNAPSHOT.jar:8.0.0-SNAPSHOT]
»  	at org.elasticsearch.bootstrap.Elasticsearch.execute(Elasticsearch.java:150) ~[elasticsearch-8.0.0-SNAPSHOT.jar:8.0.0-SNAPSHOT]
»  	at org.elasticsearch.cli.EnvironmentAwareCommand.execute(EnvironmentAwareCommand.java:86) ~[elasticsearch-8.0.0-SNAPSHOT.jar:8.0.0-SNAPSHOT]
»  	at org.elasticsearch.cli.Command.mainWithoutErrorHandling(Command.java:124) ~[elasticsearch-cli-8.0.0-SNAPSHOT.jar:8.0.0-SNAPSHOT]
»  	at org.elasticsearch.cli.Command.main(Command.java:90) ~[elasticsearch-cli-8.0.0-SNAPSHOT.jar:8.0.0-SNAPSHOT]
»  	at org.elasticsearch.bootstrap.Elasticsearch.main(Elasticsearch.java:115) ~[elasticsearch-8.0.0-SNAPSHOT.jar:8.0.0-SNAPSHOT]
»  	at org.elasticsearch.bootstrap.Elasticsearch.main(Elasticsearch.java:92) ~[elasticsearch-8.0.0-SNAPSHOT.jar:8.0.0-SNAPSHOT]

[elasticmachine]

Pinging @elastic/es-core-infra

[williamrandolph]

I found the problem. We are setting our fallback nodename by getting the HOSTNAME system property. This isn't set at test time on Windows.

https://github.com/elastic/elasticsearch/blob/master/server/src/main/java/org/elasticsearch/cli/EnvironmentAwareCommand.java#L98

I'm working on a solution now.