Bukkit/CraftBukkit — comment on commit 71a45b53a36040770b3ae066c989ffeba402bd0a
File:  line 0
By sl1nk3:

I think this commit introduced a bug when two doors (and derived objects) are placed next to each other,
Starting from this revision, you can't put two open trapdoors side to side (they automatically revert back to being closed)
And normal doors also act weird, meaning that when you attempt to close two doors, the second one will cause the first to open and vice versa.
I can't help much on tracking which code change did it, as I don't know the codebase enough though :P