File change semantics

I'm starting to move a collection of puppet manifests to Puppet 3 (3.6.2), and I have fallen foul of a change in the semantics.

In our setup, each application can use a module "duplicity::backup" to get itself backed up by a host-wide duplicity service. Doing so creates an application-specific cron jobs (i.e. file in /etc/cron.d), named "${duplicity::crontabdir}/${duplicity::crontabstem}${name}". We have $duplicity_stem = "duplicity_backup, so we get files named things like "/etc/cron.d/duplicity-backup-trac".

In addition to this, our general "duplicity" module (which is requiredbyduplicity:backup uses tidy to remove any obsolete cron jobs. Specifically, it does...

# remove any non-managed duplicity files tidy { $crontab_dir: recurse => true, matches => "${crontab_stem}*"; }

These two play together nicely in Puppet 2.7: any files in /etc/cron.d that we put there are removed, but files with unrelated names are left alone.

But things have changed in Puppet 3.6.2, which complains that there is a dependency cycle

Error: Could not apply complete catalog: Found 1 dependency cycle: (File[/etc/cron.d/duplicity-backup-trac] => Tidy[/etc/cron.d] => Class[Duplicity] => Duplicity::Backup[trac-backups] => File[/etc/cron.d/duplicity-backup-trac])

What is the best way to fix this? To keep the current functionality of deleting some of the unmanaged files in the directory, but not all of them?