Wire layouts manually navigate the inheritance hierarchy, but the data fields on the prototypes were also automatically inherited already. This meant that inheriting a wire layout prototype and changing nothing would cause the wires to be duplicated unless they were manually modified on top.
Fix is easy: just disable inheritance on the data fields.
Also, integration test for it.
(cherry picked from commit a4692004de978cda6761d4090e13ed4d8bc1fa11)
Pieter-Jan Briers