Is append_mode special cased if the selections touch or is this a bug?

[Dimension4]

I noticed that in helix 25.07.1 (a05c151), append_mode behaves differently if the selections touch each other. It seems if all selections touch each other and I press a, the selections are merged and only then helix switches into append mode. Here's a video of what I mean:

02334.mp4

I didn't want to open a bug for this right away, because I'm not sure if this is intended behavior or not. Does anyone know?