Use host-based lock for salt-formula tests

Change-Id: I2d6d948d0d941da7742d8275155f255cc900a02d
diff --git a/test-salt-formulas-pipeline.groovy b/test-salt-formulas-pipeline.groovy
index 958cd1e..2216e8a 100644
--- a/test-salt-formulas-pipeline.groovy
+++ b/test-salt-formulas-pipeline.groovy
@@ -194,7 +194,7 @@
             }
             if (kitchenFileName) {
               def kitchenEnvs = []
-              ruby.ensureRubyEnv()
+              ruby.ensureRubyEnv(host_to_lock=env.NODE_NAME)
               if (!fileExists("Gemfile")) {
                 sh("curl -s 'https://gerrit.mcp.mirantis.com/projects/salt-formulas%2Fsalt-formulas-scripts/branches/master/files/Gemfile/content' | base64 -d > ./Gemfile")
                 ruby.installKitchen()