[FIXED JENKINS-42194] Do not display a warning when ignoring post-commit hooks

(cherry picked from commit d0d9216f)

core/src/main/java/hudson/triggers/SCMTrigger.java

@@ -72,10 +72,12 @@ import jenkins.util.SystemProperties;
 import net.sf.json.JSONObject;
 import org.apache.commons.io.FileUtils;
 import org.apache.commons.jelly.XMLOutput;
+import org.apache.commons.lang.StringUtils;
 import org.jenkinsci.Symbol;
 import org.kohsuke.accmod.Restricted;
 import org.kohsuke.accmod.restrictions.DoNotUse;
 import org.kohsuke.accmod.restrictions.NoExternalUse;
+import org.kohsuke.stapler.AncestorInPath;
 import org.kohsuke.stapler.DataBoundConstructor;
 import org.kohsuke.stapler.DataBoundSetter;
 import org.kohsuke.stapler.QueryParameter;

core/src/main/resources/hudson/triggers/SCMTrigger/config.jelly

@@ -25,7 +25,7 @@ THE SOFTWARE.
 <?jelly escape-by-default='true'?>
 <j:jelly xmlns:j="jelly:core" xmlns:st="jelly:stapler" xmlns:d="jelly:define" xmlns:l="/lib/layout" xmlns:t="/lib/hudson" xmlns:f="/lib/form">
   <f:entry title="${%Schedule}" help="/descriptor/hudson.triggers.TimerTrigger/help/spec">
-    <f:textarea field="scmpoll_spec" checkUrl="'descriptorByName/hudson.triggers.TimerTrigger/checkSpec?value='+encodeURIComponent(this.value)"/>
+    <f:textarea field="scmpoll_spec"/>
   </f:entry>
   <f:entry field="ignorePostCommitHooks" title="${%Ignore post-commit hooks}">
     <f:checkbox />