dashboard: yet another utf-8 fix

R=golang-dev, dsymonds
CC=golang-dev
https://golang.org/cl/4964052

misc/dashboard/godashboard/gobuild.py

@@ -279,7 +279,7 @@ class CommitHandler(DashboardHandler):
                 n.parentnode = parenthash
                 n.user = user
                 n.date = date
-                n.desc = desc.encode('utf8')
+                n.desc = desc
                 n.put()
             db.run_in_transaction(add_commit)
             n = nodeByHash(node)