upgrade parsel and use its function to instantiate root for finding form

requirements.txt

@@ -7,4 +7,4 @@ queuelib
 six>=1.5.2
 PyDispatcher>=2.0.5
 service_identity
-parsel>=0.9.2
+parsel>=0.9.3

scrapy/http/request/form.py

@@ -7,7 +7,7 @@ See documentation in docs/topics/request-response.rst
 
 from six.moves.urllib.parse import urljoin, urlencode
 import lxml.html
-from lxml import etree
+from parsel.selector import create_root_node
 import six
 from scrapy.http.request import Request
 from scrapy.utils.python import to_bytes, is_listlike
@@ -55,15 +55,10 @@ def _urlencode(seq, enc):
     return urlencode(values, doseq=1)
 
 
-def _create_parser_from_response(response, parser_cls):
-    body = response.body_as_unicode().strip().encode('utf8') or b'<html/>'
-    parser = parser_cls(recover=True, encoding='utf8')
-    return etree.fromstring(body, parser=parser, base_url=response.url)
-
-
 def _get_form(response, formname, formid, formnumber, formxpath):
     """Find the form element """
-    root = _create_parser_from_response(response, lxml.html.HTMLParser)
+    text = response.body_as_unicode()
+    root = create_root_node(text, lxml.html.HTMLParser, base_url=response.url)
     forms = root.xpath('//form')
     if not forms:
         raise ValueError("No <form> element found in %s" % response)

setup.py

@@ -44,7 +44,7 @@ setup(
         'pyOpenSSL',
         'cssselect>=0.9',
         'six>=1.5.2',
-        'parsel>=0.9.2',
+        'parsel>=0.9.3',
         'PyDispatcher>=2.0.5',
         'service_identity',
     ],