Short description of error
Using scene layers from a different scene doesn't show the output sockets.
Exact steps for others to reproduce the error
Based on a (as simple as possible) attached .blend file with minimum amount of steps
Open the fileand re-set the scene of the right-most layer to use scene "B".
This is what you get right when you open it, or in a commit prior to the bug:
This is what you get in new files, or after you re-set the (other) scene of the renderlayer: