Comment 4 for bug 1542703

Second screenshot: I manually disabled the check that buildings cannot be on the border - so the port is not burned down after finshing.

I am not sure how to fix this issue.

1) Relax assumption 1) and give the port upon building more conquered land so that when it finishes it does not burn down. This might burn down buildings of the neighbor who looses land without military influence.
2) forbid a port space to be placed there in the first place.