[aws|elasticache] return nil on CacheClusterNotFound

lib/fog/aws/models/elasticache/clusters.rb

@@ -21,7 +21,6 @@ module Fog
             ).body['CacheClusters'].first
           )
         rescue Fog::AWS::Elasticache::NotFound
-          nil
         end
       end
 

lib/fog/aws/requests/elasticache/describe_cache_clusters.rb

@@ -21,6 +21,10 @@ module Fog
             'Action' => 'DescribeCacheClusters',
             :parser => Fog::Parsers::AWS::Elasticache::DescribeCacheClusters.new
           }.merge(options))
+        rescue Excon::Errors::NotFound => e
+          if e.response.body =~ %r{<Code>CacheClusterNotFound</Code>}
+            raise Fog::AWS::Elasticache::NotFound
+          end
         end
 
       end