[kovarex] [1.1.12] Drag placing adds unexpected undergrounds without any obstacles

[bormand]

See also: 94390

When I draw long bus lines, underground belts appear in the middle of the line without any obvious reason sometimes. There are no obstacles.

In practice it happens quite rarely (mouse sensor glitches or system lags?), but I found a way to reproduce it almost every time:

0) Create sandbox map, have some belts and underground belts in your inventory
1) Start drawing a straight belt to the right
2) Move mouse some tiles to the left
3) Quickly throw mouse to the right

Actual: unexpected underground belt appears
Expected: normal belts are placed instead

Reproducible only when smart-dragging is enabled in settings. Happens on both Win 10 and Ubuntu.

Video and log attached.

[kovarex]

Thanks, I could finally reproduce it and write a test that reproduces it as well, fixing it is the easier part now.
Edit: Fixed for 1.1.13