Minecraft wiki entry for Development_versions, associated text: MC-6077 – Comparators causes block updates while idle.
MC-7167 – Hopper's name doesn't change in its GUI after renamed in anvil.
MC-9391 – Command block arguments length.
MC-9404 – Comparator bug.
MC-9687 – Hopper don't update comparator when receiving item stack.
MC-10033 – Scoreboard accepts arguments for @p but if not found it will use a wrong name.