[Bug]: Water infrastructure total mismatch when building ship depot over water objects on owned water

[JGRennison]

Version of OpenTTD

master

Expected result

Water infrastructure total is correct

Actual result

Water infrastructure total is incorrect in the case below.

This may eventually lead to a multiplayer desync.

Steps to reproduce

1. Build two canal pieces
2. Build object(s) on one or both of these pieces
3. Build a ship depot on the two canal pieces
4. The water infrastructure total is now incorrect
5. Removing the ship depot and canal pieces now leaves a water infrastructure of 1 or 2 (depending on whether one or both tiles had objects).