Make sure %textarea and &= interact properly.

lib/haml/buffer.rb

@@ -104,15 +104,15 @@ module Haml
                     escape_html = false, nuke_inner_whitespace = false)
       tabulation = @real_tabs
 
+      result = result.to_s.rstrip
+      result = html_escape(result) if escape_html
+
       if preserve_tag
         result = Haml::Helpers.preserve(result)
       elsif preserve_script
         result = Haml::Helpers.find_and_preserve(result, options[:preserve])
       end
 
-      result = result.to_s.rstrip
-      result = html_escape(result) if escape_html
-
       has_newline = result.include?("\n")
       if in_tag && !nuke_inner_whitespace && (@options[:ugly] || !has_newline || preserve_tag)
         @buffer << result

test/haml/engine_test.rb

@@ -190,6 +190,10 @@ SOURCE
     assert_equal("<p>foo &amp; bar</p>\n", render("%p&= 'foo & bar'", :escape_html => false))
   end
 
+  def test_ampersand_equals_should_escape_before_preserve
+    assert_equal("<textarea>foo&#x000A;bar</textarea>\n", render('%textarea&= "foo\nbar"', :escape_html => false))
+  end
+
   def test_bang_equals_should_not_escape
     assert_equal("<p>\n  foo & bar\n</p>\n", render("%p\n  != 'foo & bar'", :escape_html => true))
   end