add exception for single node; revert vendor code

pkg/monitortests/clusterversionoperator/legacycvomonitortests/operators.go

@@ -13,10 +13,12 @@ import (
 	"github.com/sirupsen/logrus"
 
 	configv1 "github.com/openshift/api/config/v1"
+	clientconfigv1 "github.com/openshift/client-go/config/clientset/versioned"
 	"github.com/openshift/origin/pkg/monitor/monitorapi"
 	"github.com/openshift/origin/pkg/monitortestlibrary/platformidentification"
 	platformidentification2 "github.com/openshift/origin/pkg/monitortestlibrary/platformidentification"
 	"github.com/openshift/origin/pkg/test/ginkgo/junitapi"
+	exutil "github.com/openshift/origin/test/extended/util"
 	"k8s.io/client-go/rest"
 )
 
@@ -150,7 +152,21 @@ func testUpgradeOperatorStateTransitions(events monitorapi.Intervals, clientConf
 			availableEqualsFalseAllowed = isInUpgradeWindow(events, eventInterval) && eventInterval.To.Sub(eventInterval.From) < 10*time.Minute
 		}
 
-		if !availableEqualsFalseAllowed {
+		configClient, err := clientconfigv1.NewForConfig(clientConfig)
+		if err != nil {
+			logrus.Warnf("Error creating config client to check for Single Node configuration (unable to make exception): %v", err)
+			return "", nil
+		}
+
+		isSingleNode, err := exutil.IsSingleNode(context.Background(), configClient)
+		if err != nil {
+			logrus.Warnf("Error checking for Single Node configuration (unable to make exception): %v", err)
+			isSingleNode = false
+		}
+
+		// For now, Single node tests get an exception until we can remove this test:
+		// 'pods evicted from tainted nodes have pod disruption condition'
+		if !availableEqualsFalseAllowed && !isSingleNode {
 			return "", nil
 		}