for GitLab 8.5. use ICT Trouble Shooting Contest 5. in detail (http://icttoracon.net/tech-blog/2016/03/31/question11/) (japanese)

gitlab.py

from selenium import webdriver
from selenium.webdriver.common.keys import Keys

# GitLabのベースURL
#url = ["http://localhost:8001",
#       "http://localhost:8002"]

url = ["http://localhost:8001"]

# チームのID
team_ids = [0,1]

# WebDriver使う準備
firefox_profile = webdriver.FirefoxProfile()
firefox_profile.set_preference("browser.fixup.alternate.enabled",False) # localhostでテストしてる時に www.localhost.com に変換されたので
driver = webdriver.Firefox(firefox_profile=firefox_profile) # プロファイル読み込み
driver.implicitly_wait(1) # 要素見つかるまで待つ

for team_id in team_ids:
    # GitLabページを開く
    driver.get(url[team_id] + "/users/sign_in")
    
    # 初回ログイン
    elem_user = driver.find_elements_by_id('user_login')[0]
    elem_password = driver.find_element_by_name('user[password]')
    elem_user.send_keys("root")
    elem_password.send_keys("5iveL!fe")
    
    elem_password.send_keys(Keys.RETURN)

    # もしパスワード変更する必要があれば変更
    if( len(driver.find_elements_by_name('user[current_password]')) != 0 ):
        driver.find_element_by_name('user[current_password]').send_keys("5iveL!fe")
        driver.find_element_by_name('user[password]').send_keys("5iveL!fe")
        elem_password_cur = driver.find_element_by_name('user[password_confirmation]').send_keys("5iveL!fe")
        driver.find_element_by_name('commit').send_keys(Keys.RETURN)
    
        # 再ログイン
        elem_user = driver.find_elements_by_name('user[login]')[0]
        elem_user.send_keys("root")
        elem_password = driver.find_element_by_name('user[password]')
        elem_password.send_keys("5iveL!fe")
        
        elem_password.send_keys(Keys.RETURN)

    if ( len(driver.find_elements_by_name('user[login]')) != 0 ):
         # 再ログイン
        elem_user = driver.find_elements_by_name('user[login]')[0]
        elem_user.send_keys("root")
        elem_password = driver.find_element_by_name('user[password]')
        elem_password.send_keys("5iveL!fe")
        
        elem_password.send_keys(Keys.RETURN)
   
    # adminページへ
    driver.get(url[team_id] + "/admin/application_settings")
    
    # home_page_url 設定
    elem_home_page_url = driver.find_element_by_name('application_setting[home_page_url]')
    elem_home_page_url.send_keys(Keys.BACK_SPACE * 100)
    elem_home_page_url.send_keys("http://icttoracon.net")
    elem_home_page_url.send_keys(Keys.RETURN)

    # ログアウト
    sign_out = driver.find_elements_by_xpath('/html/body/header/div/div/div/ul/li[6]/a')[0]
    sign_out.click()

driver.close()