Improve gate mode detection

Related-Prod: https://mirantis.jira.com/browse/PRODX-29379
Change-Id: I5fd9bf8b5b8108176cbf1b73b0623dee9e6f3413
diff --git a/src/com/mirantis/mk/Gerrit.groovy b/src/com/mirantis/mk/Gerrit.groovy
index a48f554..7af195d 100644
--- a/src/com/mirantis/mk/Gerrit.groovy
+++ b/src/com/mirantis/mk/Gerrit.groovy
@@ -551,7 +551,8 @@
         }
         common.infoMsg("GERRIT_EVENT_COMMENT_TEXT is ${gerritEventCommentTextStr}")
     }
-    if (gerritEventType == 'comment-added' && gerritEventCommentTextStr =~ /^Patch Set \d+:\s.*Workflow\+1$/) {
+    def gateComment = gerritEventCommentTextStr.split('\n')[0]
+    if (gerritEventType == 'comment-added' && gateComment =~ /^Patch Set \d+:\s.*Workflow\+1$/) {
         common.infoMsg("Running in gate mode")
         res = true
     }