即使设置了首选项，python selenium也不会绕过firefox下载对话框

我正在尝试从以下链接下载文件（市场摘要（结算）— ZIP）：https : //dps.psx.com.pk/downloads

这是我的代码：

from datetime import date
from selenium import webdriver
from selenium.webdriver.common.keys import Keys
from selenium.common.exceptions import ElementClickInterceptedException
from selenium.webdriver.common.by import By
from selenium.webdriver.support.ui import WebDriverWait
from selenium.webdriver.support import expected_conditions as EC
from selenium.common.exceptions import TimeoutException
import time

profile = webdriver.FirefoxProfile()
profile.set_preference("browser.preferences.instantApply",True)
profile.set_preference("browser.helperApps.neverAsk.saveToDisk", "text/csv")
profile.set_preference("browser.helperApps.alwaysAsk.force",False)
profile.set_preference("browser.download.manager.showWhenStarting",False)
profile.set_preference("browser.download.folderList",0)


driver = webdriver.Firefox(firefox_profile=profile)
driver.get('https://dps.psx.com.pk/downloads')

start_date = driver.find_element_by_id('downloadsDatePicker')
start_date.send_keys(Keys.BACKSPACE\*0)
send_date = date(2014,1,1).strftime("%Y-%m-%d")
start_date.send_keys(send_date)
driver.find_element_by_id('downloadsSearchBtn').click()
link = '/download/mkt_summary/{}.Z'.format(send_date)
time.sleep(5)
driver.find_element_by_css_selector("a[href='{}'".format(link)).click()

即使设置了首选项，firefox仍会弹出一个下载对话框。为什么会这样，如何避免这种行为？

问题来源：stackoverflow