Comment 5 for bug 1534962

The problem seems to be that the port is a big building, and the spot just to the left of the entry is still part of the building. But then, there is no space for a border between the port and the red player's area.

A correct approach would be to reserve enough space for the construction site already. If the red player has been there before, the construction of a port should not have started (the ship should not have found the port space, similar to when the other player would own the whole territory). If the construction site was first, the tower would have destroyed it.

I think bug 1296884 describes the same problem.