Use Augeas provider to edit XML file

edit

I'm trying to use puppet to edit a file located in /opt/foo.xml

class foo {
  augeas {'foo.xml':
    incl     =>  '/tmp/foo.xml',
    context  =>  '/files/tmp/foo.xml/foo',
    lens     => "Xml.lns",
    changes   => [
      "set bar/#text herp",]
  }
}

The xml file looks like this:

<?xml version="1.0" encoding="UTF-8"?>
<foo>
  <bar>flub</bar>
</foo>

Augeas returns no diagnostic information, so it is impossible for me to know why this is not working. Can anyone else enlighten me?

Here is the output from the --debug

debug: Creating default schedules
debug: Puppet::Type::User::ProviderDirectoryservice: file /usr/bin/dscl does not ...