When older worlds are opened in Minecraft 1.13 some doors are rotatetd and the top half is missing. The bug occurs from 1.8 onwars. Version 1.7.10 or earlier is not affected.

2018-07-22_17.05.05.png   shows doors in 1.7.10

2018-07-22_17.03.28.png   the same doors in 1.8 or newer