purge_ssh_keys doesn't purge keys when multiple keys with same comment are in authorized_keys file

For all managed user accounts, I have:
purge_ssh_keys: true

However, on each puppet run, I see the warning:

Warning: /Ssh_authorized_key[root@wormhole.intern]: Cannot schedule without a schedule-containing catalog
Warning: /Ssh_authorized_key[sebastia@wormhole.intern]: Cannot schedule without a schedule-containing catalog

And those keys don't get purged.

I use saz-ssh module to manage the authorized_keys contents.
The keys that start with V4_* or V6_* in the comment are managed and pushed out to the client via that module. The others were there before,
and were expected to get purged.

1. HEADER: This file was autogenerated at 2015-01-08 20:09:40 +0100
2. HEADER: by puppet. While it can still be managed manually, it
3. HEADER: is definitely not recommended.
   from="10.0.0.27" ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQDPkwyOD0nt9ZCCZucBrWqtLEfRBcmK3PeaYVvwA3B5ezWvQdOSTUU4od2inD6yb723Zdov17yxGQo9ImywtkQV/EXKIxdWFOlfVGbxbqPhoEY2hQrBwK9OyLeyQnU3Iq7yzi4WIWCtl+ZOogxkg5u8pbq75dOJkgOEk/x7wfYU+P
   GcXXhtXc1hJUYlM9GMgZ3NCV4V1TFacPyclvmoDKWdYo6mNhecZz3XSs7r2oOCfa5N4CfAvb8pMgDJtKu8dZhmr6ac4mML6JzGhXkIZAILrO6cpRLQX+ONR+SqsmfhXsKhZjZPMadW53G2VV+Dp6kAvb1HIIqCxqCa3AB58FwD root@wormhole.intern
   from="2a01:4f8:100:818b:ffff::27" ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQDPkwyOD0nt9ZCCZucBrWqtLEfRBcmK3PeaYVvwA3B5ezWvQdOSTUU4od2inD6yb723Zdov17yxGQo9ImywtkQV/EXKIxdWFOlfVGbxbqPhoEY2hQrBwK9OyLeyQnU3Iq7yzi4WIWCtl+ZOogxkg5u8pbq75
   dOJkgOEk/x7wfYU+PGcXXhtXc1hJUYlM9GMgZ3NCV4V1TFacPyclvmoDKWdYo6mNhecZz3XSs7r2oOCfa5N4CfAvb8pMgDJtKu8dZhmr6ac4mML6JzGhXkIZAILrO6cpRLQX+ONR+SqsmfhXsKhZjZPMadW53G2VV+Dp6kAvb1HIIqCxqCa3AB58FwD root@wormhole.intern
   from="10.0.0.37" ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQC8gbP6RLzNVWD2hAI8ryl0qksU6+I0L8THRfo8/5gVwcMbkUmp5CV1VesUBnNdq9jA+si1A/5SGg1htdLDrgXdztgBtqQ6w2YwHsU2lkw2an4g2nNXCTqaWG7lcuGxCYxsEhpxZWZEgZNKIHyWnYCJE2AZdG8YLXOlECuND6h6r6
   4FL42a/02jsYopwkCgJ41qdo+LZMV7u83Ga26gQPrBrFNYJ6VIfrC2TpaE80BOEzg2aWzmGL/OU8cFZQjibzgDMu7c+Qhux3bcCAuiPlJy62vDetc6QryLQ7+z1zuav3hP+hzttpffNrXWIhDK8b4uDe9jlgdptEIb6FoYASAr sebastia@wormhole.intern
   from="2a01:4f8:100:818b:ffff::37" ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQC8gbP6RLzNVWD2hAI8ryl0qksU6+I0L8THRfo8/5gVwcMbkUmp5CV1VesUBnNdq9jA+si1A/5SGg1htdLDrgXdztgBtqQ6w2YwHsU2lkw2an4g2nNXCTqaWG7lcuGxCYxsEhpxZWZEgZNKIHyWnYCJE2AZd
   G8YLXOlECuND6h6r64FL42a/02jsYopwkCgJ41qdo+LZMV7u83Ga26gQPrBrFNYJ6VIfrC2TpaE80BOEzg2aWzmGL/OU8cFZQjibzgDMu7c+Qhux3bcCAuiPlJy62vDetc6QryLQ7+z1zuav3hP+hzttpffNrXWIhDK8b4uDe9jlgdptEIb6FoYASAr sebastia@wormhole.intern
   from="10.0.0.37" ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQC8gbP6RLzNVWD2hAI8ryl0qksU6+I0L8THRfo8/5gVwcMbkUmp5CV1VesUBnNdq9jA+si1A/5SGg1htdLDrgXdztgBtqQ6w2YwHsU2lkw2an4g2nNXCTqaWG7lcuGxCYxsEhpxZWZEgZNKIHyWnYCJE2AZdG8YLXOlECuND6h6r6
   4FL42a/02jsYopwkCgJ41qdo+LZMV7u83Ga26gQPrBrFNYJ6VIfrC2TpaE80BOEzg2aWzmGL/OU8cFZQjibzgDMu7c+Qhux3bcCAuiPlJy62vDetc6QryLQ7+z1zuav3hP+hzttpffNrXWIhDK8b4uDe9jlgdptEIb6FoYASAr V4_ROOTsebastia@wormhole.intern
   from="2a01:4f8:100:818b:ffff::37" ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQC8gbP6RLzNVWD2hAI8ryl0qksU6+I0L8THRfo8/5gVwcMbkUmp5CV1VesUBnNdq9jA+si1A/5SGg1htdLDrgXdztgBtqQ6w2YwHsU2lkw2an4g2nNXCTqaWG7lcuGxCYxsEhpxZWZEgZNKIHyWnYCJE2AZd
   G8YLXOlECuND6h6r64FL42a/02jsYopwkCgJ41qdo+LZMV7u83Ga26gQPrBrFNYJ6VIfrC2TpaE80BOEzg2aWzmGL/OU8cFZQjibzgDMu7c+Qhux3bcCAuiPlJy62vDetc6QryLQ7+z1zuav3hP+hzttpffNrXWIhDK8b4uDe9jlgdptEIb6FoYASAr V6_ROOTsebastia@wormhole.intern
   from="10.0.0.27" ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQDPkwyOD0nt9ZCCZucBrWqtLEfRBcmK3PeaYVvwA3B5ezWvQdOSTUU4od2inD6yb723Zdov17yxGQo9ImywtkQV/EXKIxdWFOlfVGbxbqPhoEY2hQrBwK9OyLeyQnU3Iq7yzi4WIWCtl+ZOogxkg5u8pbq75dOJkgOEk/x7wfYU+P
   GcXXhtXc1hJUYlM9GMgZ3NCV4V1TFacPyclvmoDKWdYo6mNhecZz3XSs7r2oOCfa5N4CfAvb8pMgDJtKu8dZhmr6ac4mML6JzGhXkIZAILrO6cpRLQX+ONR+SqsmfhXsKhZjZPMadW53G2VV+Dp6kAvb1HIIqCxqCa3AB58FwD V4_ROOTroot@wormhole.intern
   from="2a01:4f8:100:818b:ffff::27" ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQDPkwyOD0nt9ZCCZucBrWqtLEfRBcmK3PeaYVvwA3B5ezWvQdOSTUU4od2inD6yb723Zdov17yxGQo9ImywtkQV/EXKIxdWFOlfVGbxbqPhoEY2hQrBwK9OyLeyQnU3Iq7yzi4WIWCtl+ZOogxkg5u8pbq75
   dOJkgOEk/x7wfYU+PGcXXhtXc1hJUYlM9GMgZ3NCV4V1TFacPyclvmoDKWdYo6mNhecZz3XSs7r2oOCfa5N4CfAvb8pMgDJtKu8dZhmr6ac4mML6JzGhXkIZAILrO6cpRLQX+ONR+SqsmfhXsKhZjZPMadW53G2VV+Dp6kAvb1HIIqCxqCa3AB58FwD V6_ROOTroot@wormhole.intern