Fix breakage in option recognition

Fixes Homebrew/homebrew#22347.

Library/Homebrew/build_options.rb

@@ -107,7 +107,7 @@ class BuildOptions
   end
 
   def has_opposite_of? option
-    true if args.include? opposite_of option
+    @options.include? opposite_of(option)
   end
 
   def opposite_of option

Library/Homebrew/test/test_build_options.rb

@@ -3,7 +3,7 @@ require 'build_options'
 
 class BuildOptionsTests < Test::Unit::TestCase
   def setup
-    args = %w{--with-foo --with-bar --without-qux} # args fake the command line
+    args = %w{--with-foo --with-bar --without-qux}
     @build = BuildOptions.new(args)
     @build.add("with-foo")
     @build.add("with-bar")
@@ -67,4 +67,8 @@ class BuildOptionsTests < Test::Unit::TestCase
     assert !@build.has_opposite_of?("--without-qux")
     assert !@build.has_opposite_of?("--without-nonexisting")
   end
+
+  def test_actually_recognizes_implicit_options
+    assert @build.has_opposite_of?("--with-baz")
+  end
 end