Bind gem version to fix bug.

temp_file/Gemfile

@@ -6,6 +6,7 @@ if $0.to_s.scan('bundle').length==0
     system("bundle install") if !flag
   }
 end
+gem 'multipart-post', '2.1.1'
 if RUBY_VERSION.to_f <= 2.1
   gem 'concurrent-ruby', '1.1.9'
   gem 'signet', '0.11.0'