tap: improve arguments resolution

* Use `ARGV.include?` instead of `ARGV.first ==`, so users can pass
  `-v`/`-d` before the function flags(i.e. `--list-pinned` etc)
* Restore the ability to call `brew tap --flags tap/name`.

Library/Homebrew/cmd/tap.rb

@@ -3,18 +3,18 @@ require "core_formula_repository"
 
 module Homebrew
   def tap
-    if ARGV.empty?
-      puts Tap.names
-    elsif ARGV.first == "--repair"
+    if ARGV.include? "--repair"
       Tap.each(&:link_manpages)
       migrate_taps :force => true
-    elsif ARGV.first == "--list-official"
+    elsif ARGV.include? "--list-official"
       require "official_taps"
       puts OFFICIAL_TAPS.map { |t| "homebrew/#{t}" }
-    elsif ARGV.first == "--list-pinned"
+    elsif ARGV.include? "--list-pinned"
       puts Tap.select(&:pinned?).map(&:name)
+    elsif ARGV.named.empty?
+      puts Tap.names
     else
-      tap = Tap.fetch(ARGV[0])
+      tap = Tap.fetch(ARGV.named[0])
       begin
         tap.install(:clone_target => ARGV.named[1],
                     :full_clone   => ARGV.include?("--full"))