Make signature of Pathname#write compatible with Ruby 2.1+

Library/Homebrew/extend/pathname.rb

@@ -90,10 +90,10 @@ class Pathname
 
   # we assume this pathname object is a file obviously
   alias_method :old_write, :write if method_defined?(:write)
-  def write content
+  def write(content, *open_args)
     raise "Will not overwrite #{to_s}" if exist?
     dirname.mkpath
-    File.open(self, 'w') {|f| f.write content }
+    open("w", *open_args) { |f| f.write(content) }
   end
 
   # NOTE always overwrites