For what it’s worth, you did the right thing to merge it, KA101.
What ultimately happened is @BevapDin, in pull request 9180 effectively rewrote most of how the Advanced Inventory interface works. As part of that, he discovered that the keybinds were misnamed – the bindings named ITEMS_NW, _N, _NE, were actually for the southern tiles and _SW, _S, _SE were for the northern tiles.
Clearly unable to leave well enough alone (and wanting to remove confusion for future contributors), he fixed this, but anyone who has custom keybinds for any reason won’t have those keybindings update.
The unfortunate part is there’s no good way to fix this in the code, so it’s going to mean a minute or so of work for players who will need to either delete their custom bindings (these are found in config/keybindings.json in your Cataclysm folder), or just open Advanced Inventory, hit [?], and reset them.
For reference, 7, 8, and 9 are supposed to be North-West, North, and North-East, respectively; and 1, 2, and 3 are supposed to be South-West, South, and South-East, respectively.
And no blaming KA101 for this – we’d probably have merged this in regardless; he just happened to pull the trigger on it this time.