remove files from previous builds

lib/jekyll/static_file.rb

@@ -6,12 +6,26 @@ module Jekyll
     # the file
     def write(dest)
       dest_path = destination(dest)
-      return if File.exist? dest_path
+
+      # If the file exists but it's not a hardlink, we remove it and
+      # replace it with one.  This is useful when migrating from a site
+      # already built without this plugin.
+      if File.exist? dest_path
+        return if hardlink? dest_path
+        FileUtils.rm dest_path
+      end
 
       self.class.mtimes[path] = mtime
 
       FileUtils.mkdir_p(File.dirname(dest_path))
       FileUtils.ln(path, dest_path)
     end
+
+    private
+
+    # Verifies the path has hardlinks
+    def hardlink?(path)
+      File.stat(path).nlink > 1
+    end
   end
 end