Well, it's more of an abusable bug than one I want fixed..

.. Since you can only build a pier off another section of the town, if you delete the pier after you build it, and build it on the otherside of the river, you can extend your town across the river. Unfortunately this causes a big glitch with the routing of your troops into your city, as now they won't enter the sides and only enter the center of the city.
==Edit= .. I don't know how to delete this post. Turns out what happens is now I can't put more than 9 people in a town at a time now.