CI testing 0.6: all nodes complain about missing Exec[concat_/etc/shorewall/puppet/interfaces]

   - [rew06monitor1] Could not find dependent Exec[concat_/etc/shorewall/puppet/interfaces] for File[/var/lib/puppet/concat/_etc_shorewall_puppet_interfaces/fragments/100_interfaces-100-eth0] at /srv/leap/puppet/modules/concat/manifests/fragment.pp:48 
   - [rew06vpn1] Could not find dependent Exec[concat_/etc/shorewall/puppet/interfaces] for File[/var/lib/puppet/concat/_etc_shorewall_puppet_interfaces/fragments/100_interfaces-100-eth0] at /srv/leap/puppet/modules/concat/manifests/fragment.pp:48
 - [rew06mx1] Could not find dependent Exec[concat_/etc/shorewall/puppet/interfaces] for File[/var/lib/puppet/concat/_etc_shorewall_puppet_interfaces/fragments/100_interfaces-100-eth0] at /srv/leap/puppet/modules/concat/manifests/fragment.pp:48
...

the fragments file is present:

root@rew06monitor1:~# cat /var/lib/puppet/concat/_etc_shorewall_puppet_interfaces/fragments/100_interfaces-100-eth0
net eth0 detect tcpflags,blacklist,nosmurfs,norfc1918

(from redmine: created on 2014-03-07, closed on 2015-04-11, relates #2993 (closed))