--help and --version only apply as first argument

This fixes external commands that provide their own
help and version subcommands.

Closes Homebrew/homebrew#26755.

Library/Homebrew/extend/ARGV.rb

@@ -149,14 +149,6 @@ module HomebrewArgvExtension
     include? '--force-bottle'
   end
 
-  def help?
-    empty? || grep(/(-h$|--help$|--usage$|-\?$|help$)/).any?
-  end
-
-  def version?
-    include? '--version'
-  end
-
   # eg. `foo -ns -i --bar` has three switches, n, s and i
   def switch? switch_character
     return false if switch_character.length > 1

Library/brew.rb

@@ -15,11 +15,12 @@ HOMEBREW_LIBRARY_PATH = Pathname.new(__FILE__).realpath.dirname.parent.join("Lib
 $:.unshift(HOMEBREW_LIBRARY_PATH.to_s)
 require 'global'
 
-if ARGV.help?
+if ARGV.empty? || ARGV[0] =~ /(-h$|--help$|--usage$|-\?$|help$)/
+  # TODO - `brew help cmd` should display subcommand help
   require 'cmd/help'
   puts ARGV.usage
   exit ARGV.any? ? 0 : 1
-elsif ARGV.version?
+elsif ARGV.first == '--version'
   puts HOMEBREW_VERSION
   exit 0
 elsif ARGV.first == '-v'