Puppet 3.7.4-1 on CentOS7 w/ Ruby 2.0.0p353 -- undefined method `each'

Hi,

I'm seeing the below when running puppet on a new node - it seems that since moving to puppet 3.7.4 on centos 7 (new ruby?) it's unable to find a "each" method.

```
$ sudo puppet agent -vt
Info: Retrieving pluginfacts
Info: Retrieving plugin
Info: Loading facts
Info: Caching catalog for node3.local
Error: Could not create resource file /var/lib/puppet/state/resources.txt: undefined method `each' for #<String:0x00000003d896b0>
Info: Applying configuration version '1424185866'
Notice: Finished catalog run in 9.19 seconds
```

Any ideas what / why this is ?

Thanks
Alex