uniq compat for 1.8.7 on travis.

lib/fog/core/cache.rb

@@ -130,7 +130,7 @@ def self.load(model_klass, service)
       # uniqe-ify based on the total of attributes. duplicate cache can exist due to
       # `model#identity` not being unique. but if all attributes match, they are unique
       # and shouldn't be loaded again.
-      uniq_loaded = loaded.uniq { |i| i.attributes }
+      uniq_loaded = uniq_w_block(loaded) { |i| i.attributes }
       if uniq_loaded.size != loaded.size
         Fog::Logger.warning("Found duplicate items in the cache. Expire all & refresh cache soon.")
       end
@@ -160,6 +160,19 @@ def self.const_get_compat(strklass)
       end
     end
 
+    # :nodoc: compatability for 1.8.7 1.9.3
+    def self.uniq_w_block(arr)
+      ret, keys = [], []
+      arr.each do |x|
+        key = block_given? ? yield(x) : x
+        unless keys.include? key
+          ret << x
+          keys << key
+        end
+      end
+      ret
+    end
+
     # method to determine if a path can be loaded and is valid fog cache format.
     def self.valid_for_load?(path)
       data = load_cache(path)
@@ -284,4 +297,4 @@ def dump_to
       name = "#{self.class.namespace(model.class, model.service)}/#{model.identity}-#{SecureRandom.hex}.yml"
     end
   end
-end
+end