Ooops! Fixed upgrade of Rails.

vendor/rails/railties/lib/commands/servers/base.rb

@@ -0,0 +1,19 @@
+def tail(log_file)
+  cursor = File.size(log_file)
+  last_checked = Time.now
+  tail_thread = Thread.new do
+    File.open(log_file, 'r') do |f|
+      loop do
+        f.seek cursor
+        if f.mtime > last_checked
+          last_checked = f.mtime
+          contents = f.read
+          cursor += contents.length
+          print contents
+        end
+        sleep 1
+      end
+    end
+  end
+  tail_thread
+end