Issue #941

Return scavenge to on-by-default; make value for scavenge property in session.mod same as default in id-manager.xml.

jetty-server/src/main/config/modules/sessions.mod

@@ -16,4 +16,4 @@ etc/sessions/id-manager.xml
 #jetty.sessionIdManager.workerName=node1
 
 ## Period between runs of the session scavenger (in seconds)
-#jetty.sessionScavengeInterval.seconds=60
+#jetty.sessionScavengeInterval.seconds=600

jetty-server/src/main/java/org/eclipse/jetty/server/session/HouseKeeper.java

@@ -44,7 +44,7 @@ public class HouseKeeper extends AbstractLifeCycle
     protected Scheduler.Task _task; //scavenge task
     protected Runner _runner;
     protected boolean _ownScheduler = false;
-    private long _intervalMs =  0;
+    private long _intervalMs =  DEFAULT_PERIOD_MS;
    
    
     

jetty-server/src/main/java/org/eclipse/jetty/server/session/SessionContext.java

@@ -43,6 +43,7 @@ public class SessionContext
 
     public SessionContext (String workerName, ContextHandler.Context context)
     {
+        if (context != null)
             _sessionHandler = context.getContextHandler().getChildHandlerByClass(SessionHandler.class);
         _workerName = workerName;
         _context = context;