mergeDenot should prefer concerete over deferred.
mergeDenot should prefer concerete over deferred.

Previously it did this only sometimes. Now it always prefers
concrete over deferred unless the deferred info is a proper subtype
of the concrete info.

dotty-staging/dotty,spetz911/dotty,VladimirNik/dotty,som-snytt/dotty,auvik/dotty,svalaskevicius/dotty,AlexSikia/dotty,sjrd/dotty,dotty-staging/dotty,lampepfl/dotty,svalaskevicius/dotty,reactormonk/dotty,vsalvis/dotty,VladimirNik/dotty,folone/dotty,som-snytt/dotty,sjrd/dotty,spetz911/dotty,folone/dotty,sjrd/dotty,sjrd/dotty,auvik/dotty,lampepfl/dotty,densh/dotty,yusuke2255/dotty,reactormonk/dotty,dotty-staging/dotty,densh/dotty,som-snytt/dotty,angi2/dotty,lampepfl/dotty,dotty-staging/dotty,dotty-staging/dotty,sjrd/dotty,yusuke2255/dotty,angi2/dotty,vsalvis/dotty,som-snytt/dotty,lampepfl/dotty,AlexSikia/dotty,som-snytt/dotty,lampepfl/dotty