Update copyright:update task to work with rb frozen string literal pr…

…agma

Rakefile

@@ -588,7 +588,8 @@ namespace :copyright do
         :style => "#")
     Copyright.Update(
       FileList["rb/**/*.rb"],
-      :style => "#")
+      :style => "#",
+      :prefix => ["# frozen_string_literal: true\n", "\n"])
     Copyright.Update(
         FileList["java/**/*.java"])
   end

rake-tasks/copyright.rb

@@ -17,23 +17,24 @@ module Copyright
 specific language governing permissions and limitations
 under the License.
 eos
-
   def Update(files, options = {})
     style = options[:style] || "//"
     prefix = options[:prefix] || nil
 
-    notice = Copyright::NOTICE.split(/\n/).map{|line|
+    notice_lines = Copyright::NOTICE.split(/\n/).map{|line|
       (style + " " + line).rstrip + "\n"
-    }.join("")
-    notice = prefix + notice unless prefix.nil?
+    }
+    notice_lines = Array(prefix) + notice_lines
+    notice = notice_lines.join("")
 
     files.each do |f|
       lines = IO.readlines(f)
 
       index = -1
       lines.any? {|line|
         done = true
-        if line.index(style) == 0
+        if (line.index(style) == 0) ||
+           (notice_lines[index + 1] && (line.index(notice_lines[index + 1]) == 0))
           index += 1
           done = false
         end