libdeng2|SavedSession: Only populate when certain about changes

Population should only occur when there is certain knowledge that
the source data has change without FS2 being aware of it (or when
feed attachments are modified).

doomsday/libdeng2/src/game/savedsession.cpp

@@ -211,12 +211,8 @@ DENG2_PIMPL(SavedSession)
     {
         try
         {
-            // Ensure we have up-to-date info about the package contents.
-            self.populate();
-
-            File const &file = self.locate<File const>("Info");
             Block raw;
-            file >> raw;
+            self.locate<File const>("Info") >> raw;
 
             metadata.parse(String::fromUtf8(raw));