The issue here is that route values used for action selection are
'global'. That means that pages need to have a 'null' route value for
'action' and controllers need to have a 'null' route value for pages. This
is the same way that areas work.
The fix is to move the 'merge' of route values up to a level where pages
and controllers can work together. Since ADPs use the russian-doll
pattern, the fix is to run this 'merge' in the controller ADP, but after
all of the ADs have been created.
