Minor improvements of task list

appengine/swarming/elements/res/imp/tasklist/task-filters.html

Index: appengine/swarming/elements/res/imp/tasklist/task-filters.html
diff --git a/appengine/swarming/elements/res/imp/tasklist/task-filters.html b/appengine/swarming/elements/res/imp/tasklist/task-filters.html
index a2eaec58b1dc668fd1e75434f274948bda2df0a0..be4742fdc55c58f869cb3598ba68f109be2ce541 100644
--- a/appengine/swarming/elements/res/imp/tasklist/task-filters.html
+++ b/appengine/swarming/elements/res/imp/tasklist/task-filters.html
@@ -229,6 +229,11 @@
           if (col === "state") {
             params["state"] = [rest];
           } else {
+            if (col === "user" && rest === "none") {
+              // empty string means no user.  We use "none" in the UI because
+              // it is more user friendly.
+              rest = "";
+            }
             tags.push(col + this.FILTER_SEP + swarming.alias.unapply(rest))
           }
         }.bind(this));