[FIX] http_routing: fix url_for with querystring

before this commit

url_for('/fr?a=b') -> /fr/fr?a=b because /fr?a=b not in ['fr', 'en']

Now we split query string before to check that first path is a lang

addons/http_routing/models/ir_http.py

@@ -152,9 +152,9 @@ def url_lang(path_or_uri, lang_code=None):
         lang_code = pycompat.to_text(lang_code or request.context['lang'])
         lang_url_code = Lang._lang_code_to_urlcode(lang_code)
         lang_url_code = lang_url_code if lang_url_code in lang_url_codes else lang_code
-
         if (len(lang_url_codes) > 1 or force_lang) and is_multilang_url(location, lang_url_codes):
-            ps = location.split(u'/')
+            loc, sep, qs = location.partition('?')
+            ps = loc.split(u'/')
             default_lg = request.env['ir.http']._get_default_lang()
             if ps[1] in lang_url_codes:
                 # Replace the language only if we explicitly provide a language to url_for
@@ -166,7 +166,7 @@ def url_lang(path_or_uri, lang_code=None):
             # Insert the context language or the provided language
             elif lang_url_code != default_lg.url_code or force_lang:
                 ps.insert(1, lang_url_code)
-            location = u'/'.join(ps)
+            location = u'/'.join(ps) + sep + qs
     return location