Inherited faces has wrong priority

[Henrik Enberg]

Inherited faces seem to have the wrong priority.  When doing:

    (set-face-attribute 'region nil :inherit 'fringe)

The `region' face still retains its original background color despite
the `fringe' face having a different one.  The docstring for
`set-face-attribute', has this to say about inherit:

    VALUE is the name of a face from which to inherit attributes, or a
    list of face names.  Attributes from inherited faces are merged into
    the face like an underlying face would be, with higher priority than
    underlying faces.

I take this to mean that the inherited face should win when both set the
same attribute.