Only make the starts-at-0 assumption when we can't do an actual measurement

app/models/sprint.rb

@@ -44,11 +44,13 @@ class Burndown
 
     # calculate first day if not loaded from cache
     if !_series[0]
+      assume = (days[0] != Date.today)
+
       backlog ||= sprint.stories
       _series[0] = [
         backlog.inject(0) {|sum, story| sum + story.story_points.to_f }, # committed
-        0, # resolved
-        0, # accepted
+        (assume ? 0 : backlog.select {|s| s.done_ratio == 100 }.inject(0) {|sum, story| sum + story.story_points.to_f }),
+        (assume ? 0 : backlog.select {|s| s.closed? }.inject(0) {|sum, story| sum + story.story_points.to_f }),
         backlog.inject(0) {|sum, story| sum + story.estimated_hours.to_f } # remaining
       ]
       cache(days[0], _series[0])