Fix instance variables in dynamic pages

middleman-core/features/instance_vars.feature

@@ -0,0 +1,9 @@
+Feature: Instance Variables
+  Scenario: A dynamic page template using instance variables
+    Given the Server is running at "instance-vars-app"
+    When I go to "/a.html"
+    Then I should see "A: 'set'"
+    Then I should see "B: ''"
+    When I go to "/b.html"
+    Then I should see "A: ''"
+    Then I should see "B: 'set'"

middleman-core/fixtures/instance-vars-app/config.rb

@@ -0,0 +1,7 @@
+page "a.html", :proxy => 'content.html', :ignore => true do
+  @a = "set"
+end
+
+page "b.html", :proxy => 'content.html', :ignore => true do
+  @b = "set"
+end

middleman-core/fixtures/instance-vars-app/source/content.html.erb

@@ -0,0 +1,2 @@
+A: '<%= @a %>'
+B: '<%= @b %>'

middleman-core/fixtures/instance-vars-app/source/layout.erb

@@ -0,0 +1 @@
+<%= yield %>

middleman-core/lib/middleman-core/core_extensions/rendering.rb

@@ -96,7 +96,7 @@ module Middleman
         # @param [Hash] locs
         # @param [Hash] opts
         # @return [String]
-        def render_template(path, locs={}, opts={})
+        def render_template(path, locs={}, opts={}, blocks=[])
           # Detect the remdering engine from the extension
           extension = File.extname(path)
           engine = extension[1..-1].to_sym
@@ -107,6 +107,9 @@ module Middleman
           # Use a dup of self as a context so that instance variables set within 
           # the template don't persist for other templates.
           context = self.dup
+          blocks.each do |block|
+            context.instance_eval(&block)
+          end
 
           # Store current locs/opts for later
           @current_locs = locs, @current_opts = opts

middleman-core/lib/middleman-core/sitemap/resource.rb

@@ -125,14 +125,11 @@ module Middleman
             app.data.store("page", md[:page])
           end
         
-          md[:blocks].each do |aBlock|
-            app.instance_eval(&aBlock)
-          end
-      
-          app.instance_eval(&block) if block_given?
-        
+          blocks = md[:blocks].dup rescue []
+          blocks << block if block_given?
+
           app.current_path ||= self.destination_path
-          app.render_template(source_file, locs, opts)
+          app.render_template(source_file, locs, opts, blocks)
         end
       end