This doesn't really have much to do about packing or rP21630, it's changing the attack-move sub-orders from forced to not forced so units won't chase targets anymore.
In particular, units in defensive stance won't attack any units on the route until they're close enough to their destination. That doesn't seem correct to me, but I guess we'll see how many bug reports we get.

In rP21786#30465, @temple wrote:

This doesn't really have much to do about packing or rP21630, it's changing the attack-move sub-orders from forced to not forced so units won't chase targets anymore.

Yes, the term packing is not necessarily the best one, but the problem is really with packing units which are now in standground stance by default in order not to chase. So why would move-attack force them to chase if the player don't want it!

In particular, units in defensive stance won't attack any units on the route until they're close enough to their destination. That doesn't seem correct to me, but I guess we'll see how many bug reports we get.

And why would you choose defensive stance and not agressive one is that's what you want.

Orders not directly set by players (and sub-orders of move-attack are in that category) should not be forced.

In rP21786#30465, @temple wrote:

This doesn't really have much to do about packing or rP21630, it's changing the attack-move sub-orders from forced to not forced so units won't chase targets anymore.
In particular, units in defensive stance won't attack any units on the route until they're close enough to their destination. That doesn't seem correct to me, but I guess we'll see how many bug reports we get.

Yeah I'm not really digging that. Right now defensive is the only stance where units will attack without suiciding themselves horribly. Taking that away would make unit AI worse than it already is and would make controlling units next to impossible.