same page, render.html is ok,but execute is error encoding

Test one(execute):

script = ''' 
function main(splash)
    splash:on_request(function(request)
        request:set_proxy{host="111.2.131.233", port=80}
        --request:set_header("Accept-Language", "zh-CN,zh;q=0.8")
        request:set_header("Accept-Encoding", "gzip,deflate")
        --request:set_header("Accept-Encoding", "*")
        --request:set_header("Accept", "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8")
        --request:set_header("User-Agent", "Mozilla/5.0 (X11; CrOS i686 2268.111.0) AppleWebKit/536.11 (KHTML, like Gecko) Chrome/20.0.1132.57 Safari/536.11")
        --request:set_header("Connection", "keep-alive")
        --request:set_header("Cache-Control", "max-age=0")
    end)
    --splash:go("http://10.0.8.213:8000/sample/splash/")
    splash:go("http://www.qichacha.com/firm_JS_15d5e3cbf3f484215f9293a9b3489905.shtml")
    splash:wait(3)
    --splash:runjs("document.getElementById('iframe1').innerHTML= frames[0].document.body.innerHTML")
    --splash:runjs("var iis = document.getElementsByTagName('iframe');for(var i = 0;i < iis.length; i++){iis[i].innerHTML=frames[i].document.body.innerHTML}")
    return splash:html()
end
'''
res = requests.get('http://127.0.0.1:8050/execute', params={
    'lua_source': script}, timeout=10)
t = res.text
print t

Result One: �s��k��="" ��|am��f�gu~��v�rn�v7�j��m��Ϊ��k��v��q��l}fj�^j�nu�czҙ�="" �<ңn9��!jk"��y�<�g�!&ʉ"�ẗ��j�!��g��g��q�f��="" ��9�ەˌp�g��Ư="" n���.��#gi��!��7z�!�66��_lc��x�iiu�i}��¹��]$j`�x��q�@��[��|1v��7�g�ig�h+͌��p'6��в�o��r0�[��t��|m�u�n��n��u�q="">��5.f\xqaF�;#g��.w�xfx�l�O�oM$.�L|�/y��?�5W��?@�m� Te&��cQ/��ƽ��؛��r�.̮�ݾa�M�X ��m�~-� F/w�Q FB�g�p�xM�k��C[rdp�o��E��~�-z$��=�{��af��D��.�r{�>�� t��F�= w��ُ�� /f �se��8c.|o�&Z�9.1��0x 8Em��:�"�x.�͊�̵b�?��:�{#h|�)Q��굟 @��c��S8QW$��˖w��6��k��r�R�}; ��n-6֦��!~E;?��p�w�,��QO�{r �º�v_��?� ��㼉�s;��]�U�?Q��2@r��&O�.�g캯W��x��[w��e �؞;��{C�U�D��@yx� �t�M��Q�>�I�� {��Noh^��'��9��틄�� ~�W�iO�?��{�G�E��JN�� )Qga �U�cC��E�.k�O�~��V��|��'��=�P e�V&eDWLg��;��b��u�<~�t��:��OL�=y��??�?��'R��/J�2�CK_�p�"�F[[=B��h��>�:ڹ�4g8��;IJR��ˊ�!�nw ��:�[P�H�"��\��N��v�^.G.�H��Ñ��[LD��.��Q�B��6��=.g`�o>U�uV��?�Nsr�ASr��g)&q�:{j�a�.AV �5zF��9Z�6��x��̐��-ڸ|��aG��[�Q@l��B��^}ܘ�6�HI7m�+��W��]m,o!/G]}�^�V�Yߛ�S�7��{��pS��ʲVE��f�a;�oj7��|� i��e�Fx��0!|+��]r��Ny.�x��c�Ћx��_��F�Cx��G��{��#��w��g9q�w�k�ⷅz�� ]8��x9s�E%��4�%��e,#p�#MX�>HIp��K��¯�2.4�z��@��sM��i�3ʅ��!��<��h��&?GO"��砲��仼+��r�p�</0x�nwp></m��\�ᶠ7�q9����]w �֍></i��}��xl<�k�2pq�>

Test two(render.html):

res = requests.get('http://127.0.0.1:8050/render.html', params={'url': 'http://www.qichacha.com/firm_JS_15d5e3cbf3f484215f9293a9b3489905.shtml',
    'proxy': 'http://111.2.131.233:80'}, headers={'Accept-Encoding': 'gzip,deflate'}, timeout=10)
t = res.text
print t

Result Two: test2

In the test one, when i set request:set_header("Accept-Encoding", "*"),the result is right.

What is the reason?

scrapinghub / splash

same page, render.html is ok,but execute is error encoding #423