System Information
Win10 64bit; 24 gigs RAM; ATI 7xxx GPU; Ivy Bridge i7 CPU

Blender Version
Broken: Hash 66ef0b8
Worked: Hash 253281f

Short description of error
With CPU rendering at least, bumps created with the bump node no longer render on meshes if they are making any use of the displacement socket in the material output node (but that only occurs during the F12 render,

Exact steps for others to reproduce the error
Download the .blend file and see the bump texture working in the rendered view, now render the scene using F12 and watch how those details no longer show up. Notice how the preview mesh in the material window is completely devoid of bumps, and how they suddenly appear when the connection to the displacement socket is removed.

.blend

EDIT: the regression is bigger than I thought, right now you can't use the bump node at all if there's any connection whatsoever to the bump/displacement socket in the output node (not mattering if you use true displacement or not, the report is updated)