Fix inheritable attributes mutable by subclasses

child classes should be able to reconfigure inherited attributes without stomping each other

lib/httparty/module_inheritable_attributes.rb

@@ -17,7 +17,7 @@ module HTTParty
       def inherited(subclass)
         @mattr_inheritable_attrs.each do |inheritable_attribute|
           instance_var = "@#{inheritable_attribute}"
-          subclass.instance_variable_set(instance_var, instance_variable_get(instance_var))
+          subclass.instance_variable_set(instance_var, instance_variable_get(instance_var).clone)
         end
       end
     end

spec/httparty_spec.rb

@@ -308,6 +308,27 @@ describe HTTParty do
     end
   end
 
+  describe "two child classes inheriting from one parent" do
+    before(:each) do
+      @parent = Class.new do
+        include HTTParty
+      end
+
+      @child1 = Class.new(@parent)
+      @child2 = Class.new(@parent)
+    end
+
+    it "does not modify each others inherited attributes" do
+      @child1.default_params :joe => "alive"
+      @child2.default_params :joe => "dead"
+
+      @child1.default_options.should == { :default_params => {:joe => "alive"} }
+      @child2.default_options.should == { :default_params => {:joe => "dead"} }
+
+      @parent.default_options.should == { }
+    end
+  end
+
   describe "#get" do
     it "should be able to get html" do
       stub_http_response_with('google.html')