Revert "bottle: allow --keep-old to ignore same sha256s."

This reverts commit ec143749.

Library/Homebrew/cmd/bottle.rb

@@ -391,14 +391,10 @@ module Homebrew
 
                 if !tag.empty?
                   if !bottle_hash["bottle"]["tags"][tag].to_s.empty?
-                    old_value = bottle_hash["bottle"]["tags"][tag][key].to_s
-                    if value != old_value
-                      mismatches << "#{key} => #{tag}"
-                    end
-                    next
+                    mismatches << "#{key} => #{tag}"
+                  else
+                    bottle.send(key, value => tag.to_sym)
                   end
-
-                  bottle.send(key, value => tag.to_sym)
                   next
                 end