nanoc.rb in nanoc-4.4.4

- old
+ new

@@ -31,9 +31,10 @@
 require 'fileutils'
 require 'forwardable'
 require 'pathname'
 require 'pstore'
 require 'set'
+require 'singleton'
 require 'tempfile'
 require 'thread'
 require 'time'
 require 'yaml'
 require 'English'