load static resources from the path dedicated to a specific version.

This "/static/VERSION/abc/def.ghi" path is interpreted by stapler to be
  the same thing as "/abc/def.ghi", but this avoids the stale cache
  problem when the user upgrades to new Hudson. Stapler also sets a long
  future expiration dates for such static resources.


git-svn-id: https://hudson.dev.java.net/svn/hudson/trunk/hudson/main@4099 71c3de6d-444a-0410-be80-ed276b4c234a

core/src/main/java/hudson/WebAppMain.java

@@ -108,6 +108,11 @@ public class WebAppMain implements ServletContextListener {
         Hudson.VERSION = ver;
         context.setAttribute("version",ver);
 
+        if(ver.equals("?"))
+            Hudson.RESOURCE_PATH = "";
+        else
+            Hudson.RESOURCE_PATH = "/static/"+Util.getDigestOf(ver).substring(0,8);
+
         Trigger.init(); // start running trigger
 
         // trigger the loading of changelogs in the background,