Fix for issue where 'clone' resource sometimes attempts to notify 'set permission' resource to :run when it doesn't exist, resulting in:

[2013-01-30T15:16:30+13:00] FATAL: Chef::Exceptions::ResourceNotFound: resource execute[clone repository] is configured to notify resource execute[set permission] with action run, but execute[set permission] cannot be found in the resource collection. execute[clone repository] is defined in /root/chef/cookbooks/mercurial/providers/default.rb:49:in `block in class_from_file'