fix adding text error occur on sometimes that will overwrite the whole file

announcement.gemspec

@@ -76,8 +76,8 @@ all_template.each do |folder|
           check_texts.each do |check_text|
             if !texts.include?(check_text)
               puts "editing #{folder}assets/stylesheets/template/base/_variables.scss"
-              File.open(filename, 'a') do |file|
-                file.puts check_text
+              File.open(filename, 'w') do |file|
+                file.write(texts + check_text)
               end
             end
           end