Tuning distance estimations to intersections

From an email report:

When I come to an intersection where the navigation indicates I should turn, the distance to the turn is not zero in Sidecar. It’s some other number. Here are some shots I grabbed today, showing that I’m at an intersection, where I should clearly turn, but it indicates that I should drive another 18 or 16 metres (which would put me on the other side of the intersection). I noticed this on a different road where it said I still had 51 metres to go but I was at my turn. This can be confusing in a dense area of streets that are close together.

To be fair, I stopped behind the crosswalks putting me 2-3 metres back from the road itself, but 16 metres is a lot more than that. I’m afraid I didn’t notice if it ever zeroed on the turn (I was driving at the time 😊).

The report concerns Sidecar's turn-distance display but names no source files, tests, or entry points. Start by reproducing the issue at an intersection and trace where the displayed distance is calculated. Done means the distance no longer shows a substantially incorrect remaining value when the vehicle reaches a turn.