Minecraft wiki entry for Development_versions, associated text: MC-6032 – Comparator outputs "pulse" when side signal is on.
MC-6039 – The delay of the comparator is inconsistent.
MC-6077 – Comparators causes block updates while idle.
MC-6536 – Comparator is miscounting Hopper's contents.
MC-6640 – Comparators trying to lock Repeaters even if their output is 0 (graphical).
MC-6941 – SRV is no longer used to lookup servers.
MC-6951 – High-res texture pack items have garbage on edges.
MC-7087 – Mining activator rail isn't boosted by pickaxe.
MC-8172 – TNT defuses when traveling between dimensions.