Merge pull request #3362 from saschagrunert/latest-version

Set `KUBE_CROSS_VERSION` to latest if required

pkg/gcp/gcb/gcb.go

@@ -377,6 +377,18 @@ func (g *GCB) SetGCBSubstitutions(toolOrg, toolRepo, toolRef, gcsBucket string)
 		logrus.Infof("KubeCross version not set for %s, falling back to latest", g.options.Branch)
 	}
 
+	if g.options.Branch != git.DefaultBranch {
+		kcVersionLatest, err := kc.Latest()
+		if err != nil {
+			return gcbSubs, fmt.Errorf("retrieve latest kube-cross version: %w", err)
+		}
+
+		// if kcVersionBranch is empty, the branch does not exist yet, we use
+		// the latest kubecross version
+		if kcVersionBranch == "" {
+			kcVersionBranch = kcVersionLatest
+		}
+	}
 	gcbSubs["KUBE_CROSS_VERSION"] = kcVersionBranch
 
 	switch {