got rid of Pry.commands.dup in pry_class for run_command as it fixes Rubinius compatibility and other subtle bugs related to YARV and RBX not correctly dupping singleton class ancestor chains

lib/pry/pry_class.rb

@@ -187,12 +187,7 @@ class Pry
 
     null_output = Object.new.tap { |v| v.instance_eval { def puts(*) end } }
 
-    # FIXME! ugly hack to get around broken methods in both YARV and RBX
-    if RUBY_VERSION =~ /1.9/
-      commands = options[:commands].dup
-    else
-      commands = options[:commands].clone
-    end
+    commands = options[:commands]
 
     commands.output = options[:show_output] ? options[:output] : null_output
     commands.target = Pry.binding_for(options[:context])