Note: this bug doesn't happen in emacs 24.3.

1. emacs -Q
2. M-x load-theme RET deeper-blue RET
3. open a patch in diff-mode.

Face: diff-added (sample) (customize this face)

Documentation:
`diff-mode' face used to highlight added lines.

Defined in `diff-mode.el'.

           Family: unspecified
          Foundry: unspecified
            Width: unspecified
           Height: unspecified
           Weight: unspecified
            Slant: unspecified
       Foreground: unspecified
DistantForeground: unspecified
       Background: unspecified
        Underline: unspecified
         Overline: unspecified
   Strike-through: unspecified
              Box: unspecified
          Inverse: unspecified
          Stipple: unspecified
             Font: unspecified
          Fontset: unspecified
          Inherit: unspecified