Fix parsing extra whitespace in code blocks

lib/gollum/markup.rb

@@ -459,11 +459,12 @@ module Gollum
     # Returns the placeholder'd String data.
     def extract_code(data)
       data.gsub!(/^([ \t]*)``` ?([^\r\n]+)?\r?\n(.+?)\r?\n\1```\r?$/m) do
-        id     = Digest::SHA1.hexdigest("#{$2}.#{$3}")
+        lang   = $2 ? $2.strip : nil
+        id     = Digest::SHA1.hexdigest("#{lang}.#{$3}")
         cached = check_cache(:code, id)
         @codemap[id] = cached   ?
           { :output => cached } :
-          { :lang => $2, :code => $3, :indent => $1 }
+          { :lang => lang, :code => $3, :indent => $1 }
         "#{$1}#{id}" # print the SHA1 ID with the proper indentation
       end
       data

test/test_markup.rb

@@ -478,6 +478,20 @@ np.array([[2,2],[1,3]],np.float)
     assert_markup_highlights_code Gollum::Markup, rendered
   end
 
+  test "code with trailing whitespace" do
+    content = <<-END
+shoop da woop
+
+``` python 
+np.array([[2,2],[1,3]],np.float)
+```
+    END
+
+    # rendered with Gollum::Markup
+    page, rendered = render_page(content)
+    assert_markup_highlights_code Gollum::Markup, rendered
+  end
+
   def assert_markup_highlights_code(markup_class, rendered)
     assert_match /div class="highlight"/, rendered, "#{markup_class} doesn't highlight code\n #{rendered}"
     assert_match /span class="n"/, rendered, "#{markup_class} doesn't highlight code\n #{rendered}"