Hi!
I recently made the following change in the manifest:
nginx::server { 'repo':
listen_port => '7897',
- sname => "repo",
+ sname => "repo repo-${downcase(::location)}.rvzr.net",
docroot => '/var/repo'
}

That lead to deleting the class from the class as as I understood because of validation problems, but puppet applied everything ok.
and because of Bug #2394 it did delete class from one of the hosts that lead to produstion issues.