[build] fix JRuby install

Author: titusfortner

third_party/jruby/update.rb

@@ -1,3 +1,4 @@
+require 'fileutils'
 require "open-uri"
 require "rake"
 
@@ -12,7 +13,7 @@
 
 puts "Downloading #{jar_name} from #{url}..."
 File.open(jar_name, "wb") do |write_file|
-  open(url, "rb") do |read_file|
+  URI.open(url, "rb") do |read_file|
     write_file.write(read_file.read)
   end
 end
@@ -21,15 +22,17 @@
 gems.each do |gem_name, gem_version|
   sh "java", "-jar", jar_name, "-S", "gem", "install", "-i", "./#{gem_name}", gem_name, "-v", gem_version
   sh "jar", "uf", jar_name, "-C", gem_name, "."
-  rm_rf gem_name
+  FileUtils.rm_rf gem_name
 end
 
 puts "Bumping VERSION..."
 jruby_version = `java -jar #{jar_name} -version`.split("\n").first
 File.write("VERSION", "#{jruby_version}\n")
 
-cp jar_name, File.realpath("third_party/jruby/jruby-complete.jar")
-cp "VERSION", File.realpath("third_party/jruby/VERSION")
+destination = File.realpath("third_party/jruby/")
+FileUtils.rm_f("#{destination}jruby-complete.jar") if File.exist?("#{destination}jruby-complete.jar")
+FileUtils.cp(jar_name, "#{destination}jruby-complete.jar")
+FileUtils.cp("VERSION", "#{destination}VERSION")
 
 puts `ls -l third_party/jruby/`