Python 模拟登录豆瓣的验证码一直错误

我使用的是 python2+urllib2+cookielib 来模拟登录豆瓣。但是很奇怪的是我获取了验证码之后，再尝试登录一直显示验证码错误。后来我打印了一下获取到的 cookie,发现只有一行,也就是并不全。这会不会是登录失败的原因？求各位 v 友帮忙看一下，实在不知道错哪了。。。。谢谢，代码如下。

import urllib
import urllib2
import cookielib
import re

login_url = 'https://www.douban.com/accounts/login'

#set opener
cookiejar = cookielib.LWPCookieJar()
handler = urllib2.HTTPCookieProcessor(cookiejar)
opener = urllib2.build_opener(handler)
urllib2.install_opener(opener)

text = urllib2.urlopen(login_url).read()


cookie = ""
for item in cookiejar:
	cookie += item.name + '=' + item.value + ';' 
print cookie

#get captcha image
image_pattern = re.compile('<img.*?src="(.*?)" alt.*?/>')
picture_url = re.findall(image_pattern, text)
picture = urllib2.urlopen((str(picture_url[0]))).read()

#save captcha image
captcha_image = open('./image.jpg', 'wb')
captcha_image.write(picture)
captcha_image.close()

#get captcha id
pattern = re.compile('<input.*?captcha-id".*?value=(.*?)/>', re.S)
captcha_id = re.findall(pattern, text)

#input secret_code 
captcha_code = raw_input('input the code')

#set post_data
params = {}
params['source'] = 'None'
params['redir'] = 'https://www.douban.com'
params['form_email'] = 'xxxxxx@qq.com'
params['form_password'] = 'xxxxxx'
params['captcha-solution'] = captcha_code
params['captcha-id'] = str(captcha_id[0])
params['login'] = '登录'
postdata = urllib.urlencode(params)
headers = {
		"Host": "accounts.douban.com",
		"User-Agent": "Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Firefox/52.0",
		"Accept": "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8",
		"Accept-Language": "en-US,en;q=0.5",
		"Referer": "https://www.douban.com/accounts/login",
		"Cookie": cookie,
		"Connection":"keep-alive"
		}


#login
req = urllib2.Request(login_url, postdata, headers)
response = urllib2.urlopen(req)

print response.read()