Fix Locals need to be shallow cloned.

Resolves #20. `prop_template` prebuilds an array of options before
handling it off to handle_collection to build. I recall this being
somewhat related to faster collection rendering. Unfortunately,
the trade off is that we have to be cognizant of how we mutate deeply
nested options as those can be the same object. In this case, I missed
a required clone on locals.

lib/props_template/extensions/partial_renderer.rb

@@ -137,7 +137,7 @@ def refine_options(options, item = nil)
 
       partial, rest = [*options[:partial]]
       rest = (rest || {}).clone
-      locals = rest[:locals] || {}
+      locals = (rest[:locals] || {}).clone
       rest[:locals] = locals
 
       if item

spec/extensions/partial_render_spec.rb

@@ -299,6 +299,22 @@
     ])
   end
 
+  it "renders an array with cloned :locals" do
+    json = render(<<~PROPS)
+      emails = [
+        {value: '[email protected]'},
+        {value: '[email protected]'},
+      ]
+      json.array! emails, partial: ['simple_as', locals: {}] do
+      end
+    PROPS
+
+    expect(json).to eql_json([
+      {foo: "[email protected]"},
+      {foo: "[email protected]"}
+    ])
+  end
+
   it "renders an an empty array" do
     json = render(<<~PROPS)
       json.array! [], {partial: 'simple'} do

spec/fixtures/_simple_as.json.props

@@ -0,0 +1 @@
+json.foo simple_as[:value]