The original fix was lost when Winstone became 2.0

changelog.html

@@ -91,6 +91,8 @@ Upcoming changes</a>
   <li class=bug>
     TestObject doesn't replace '%' character
     (<a href="https://issues.jenkins-ci.org/browse/JENKINS-21707">issue 21707</a>)
+  <li class=bug>
+    "java -jar jenkins.war" should use unique session cookie for users who run multiple Jenkins on the same host.
 </ul>
 </div><!--=TRUNK-END=-->
 

war/pom.xml

@@ -103,7 +103,7 @@ THE SOFTWARE.
       -->
       <groupId>org.jenkins-ci</groupId>
       <artifactId>winstone</artifactId>
-      <version>2.0</version>
+      <version>2.1</version>
       <scope>test</scope>
     </dependency>
     <dependency>