upgrade: don't rely on return value of 'onoe'

Library/Homebrew/cmd/upgrade.rb

@@ -17,8 +17,10 @@ module Homebrew extend self
       outdated = ARGV.formulae.select do |f|
         if f.installed?
           onoe "#{f}-#{f.installed_version} already installed"
+          false
         elsif not f.rack.directory? or f.rack.subdirs.empty?
           onoe "#{f} not installed"
+          false
         else
           true
         end