brew-upgrade: Respect --ignore-dependencies flag

Passing `--ignore-dependencies` to `brew upgrade` will now have the desired
effect.

Library/Homebrew/cmd/upgrade.rb

@@ -29,6 +29,7 @@ module Homebrew extend self
       end
     end
 
+    unless ARGV.include? '--ignore-dependencies'
       # Expand the outdated list to include outdated dependencies then sort and
       # reduce such that dependencies are installed first and installation is not
       # attempted twice. Sorting is implicit the way `recursive_deps` returns
@@ -37,6 +38,7 @@ module Homebrew extend self
       outdated.map!{ |f| f.recursive_deps.reject{ |d| d.installed?} << f }
       outdated.flatten!
       outdated.uniq!
+    end
 
     if outdated.length > 1
       oh1 "Upgrading #{outdated.length} outdated package#{outdated.length.plural_s}, with result:"