The test failed on branch=master, cloud=gce:
test artifacts and logs in: /home/agent/work/.go/src/github.com/cockroachdb/cockroach/artifacts/scaledata/distributed-semaphore/nodes=6/run_1
	cluster.go:2687,scaledata.go:126,scaledata.go:56,test_runner.go:767: monitor failure: unexpected node event: 1: dead
		(1) attached stack trace
		  -- stack trace:
		  | main.(*monitor).WaitE
		  | 	/home/agent/work/.go/src/github.com/cockroachdb/cockroach/pkg/cmd/roachtest/cluster.go:2675
		  | main.(*monitor).Wait
		  | 	/home/agent/work/.go/src/github.com/cockroachdb/cockroach/pkg/cmd/roachtest/cluster.go:2683
		  | main.runSqlapp
		  | 	/home/agent/work/.go/src/github.com/cockroachdb/cockroach/pkg/cmd/roachtest/scaledata.go:126
		  | main.registerScaleData.func1
		  | 	/home/agent/work/.go/src/github.com/cockroachdb/cockroach/pkg/cmd/roachtest/scaledata.go:56
		  | main.(*testRunner).runTest.func2
		  | 	/home/agent/work/.go/src/github.com/cockroachdb/cockroach/pkg/cmd/roachtest/test_runner.go:767
		  | runtime.goexit
		  | 	/usr/local/go/src/runtime/asm_amd64.s:1374
		Wraps: (2) monitor failure
		Wraps: (3) unexpected node event: 1: dead
		Error types: (1) *withstack.withStack (2) *errutil.withPrefix (3) *errors.errorString

	cluster.go:1666,context.go:140,cluster.go:1655,test_runner.go:848: dead node detection: /home/agent/work/.go/src/github.com/cockroachdb/cockroach/bin/roachprod monitor teamcity-2676655-1613372337-71-n7cpu4 --oneshot --ignore-empty-nodes: exit status 1 7: skipped
		4: 4952
		2: 5311
		3: 5370
		6: 5127
		1: dead
		5: 5081
		Error: UNCLASSIFIED_PROBLEM: 1: dead
		(1) UNCLASSIFIED_PROBLEM
		Wraps: (2) attached stack trace
		  -- stack trace:
		  | main.glob..func14
		  | 	/home/agent/work/.go/src/github.com/cockroachdb/cockroach/pkg/cmd/roachprod/main.go:1147
		  | main.wrap.func1
		  | 	/home/agent/work/.go/src/github.com/cockroachdb/cockroach/pkg/cmd/roachprod/main.go:271
		  | github.com/spf13/cobra.(*Command).execute
		  | 	/home/agent/work/.go/src/github.com/cockroachdb/cockroach/vendor/github.com/spf13/cobra/command.go:830
		  | github.com/spf13/cobra.(*Command).ExecuteC
		  | 	/home/agent/work/.go/src/github.com/cockroachdb/cockroach/vendor/github.com/spf13/cobra/command.go:914
		  | github.com/spf13/cobra.(*Command).Execute
		  | 	/home/agent/work/.go/src/github.com/cockroachdb/cockroach/vendor/github.com/spf13/cobra/command.go:864
		  | main.main
		  | 	/home/agent/work/.go/src/github.com/cockroachdb/cockroach/pkg/cmd/roachprod/main.go:1852
		  | runtime.main
		  | 	/usr/local/go/src/runtime/proc.go:204
		  | runtime.goexit
		  | 	/usr/local/go/src/runtime/asm_amd64.s:1374
		Wraps: (3) 1: dead
		Error types: (1) errors.Unclassified (2) *withstack.withStack (3) *errutil.leafError