[0.17.41] Cancelling half an underground belt upgrade results in partial upgrade

[superwad]

It's possible to force a partial upgrade of an underground belt pair using the default upgrade planner. I tested this with Creative Mode mod enabled only.

Steps:
1. Only have a few construction bots in your personal roboport
2. Lay down a few yellow underground belt pairs
3. Use the default upgrade planner to select all the yellow belts
4. While the robots are upgrading (and both ends upgrade as expected), you need to shift-drag the upgrade planner over one half of a pair

Expected:
5. Upgrade is either cancelled for both ends of the pair (likely the expected behaviour), or the other half forces the upgrade of the "cancelled" item

Actual:
5. The robot upgrades the uncancelled half of the belt pair, resulting in a broken connection

[boskid]

Duplicate 68271 (not a bug)

[superwad]

Unfortunate, I'd be curious to know why this behaviour was decided to be best for player experiences. I've had multiple examples of critical belt lines running dry because of a stray upgrade planner undo.