Fix partial layouts.

Closes gh-403
Closes gh-412
Closes gh-417

doc-src/HAML_CHANGELOG.md

@@ -3,6 +3,10 @@
 * Table of contents
 {:toc}
 
+## 3.1.3 (Unreleased)
+
+* Stop partial layouts from being displayed twice.
+
 ## 3.1.2
 
 * If the ActionView `#capture` helper is used in a Haml template but without any Haml being run in the block,

lib/haml/helpers/action_view_mods.rb

@@ -88,6 +88,7 @@ module ActionView
       module CaptureHelper
         def capture_with_haml(*args, &block)
           if Haml::Helpers.block_is_haml?(block)
+            _hamlout = eval('_hamlout', block.binding) # Necessary since capture_haml checks _hamlout
             value = nil
             buffer = capture_haml(*args) { value = yield(*args) }
             str =