Don't need to do anything tricky any more.

Don't need to do 'constantOnceLoaded' as we can now just do
 - wait until loaded -- then constant.

client/views/posts/post_edit.html

@@ -1,7 +1,7 @@
 <template name="post_edit">
   {{#if canEdit "Posts" "replace"}}
     <div class="grid submit">
-      {{#with post}}
+      {{#constant}}{{#with post}}
         <form class="grid-block form-horizontal">
           <div class="control-group">
             <label class="control-label">Title</label>
@@ -42,7 +42,7 @@
             <input type="submit" value="Submit" />
           </div>
         </form>
-      {{/with}}
+      {{/with}}{{/constant}}
     </div>
   {{/if}}
 </template>

client/views/posts/post_edit.js

@@ -7,28 +7,7 @@
 
 Template.post_edit.helpers({
   post: function(){
-    // The idea here is to isolate the call to findOne() so that it stops
-    // being reactive once data is found. The reason being that server scoring
-    // updates will 'change' the post, and meteor will overwrite the user's
-    // input, even if preserve is set. 
-    // Kind of like {{#constant}}, except it waits for data.
-    // 
-    // XXX: either figure out a different approach, or factor this out and
-    // use everywhere.
-    var outerContext = Meteor.deps.Context.current;
-    var innerContext = new Meteor.deps.Context;
-    var post;
-    
-    innerContext.onInvalidate(function() {
-      // we don't need to send the invalidate through anymore if post is set
-      post || outerContext.invalidate();
-    });
-    
-    innerContext.run(function() {
-      post = Posts.findOne(Session.get('selectedPostId'));
-    });
-    
-    return post;
+    return Posts.findOne(Session.get('selectedPostId'));
   },
   categories: function(){
     return Categories.find();