Bad status line exception while opening a page on django development server

Question

I am executing selenium test cases via Proboscis, for good reporting of test results. I have the following test case written

from selenium import webdriver 
from selenium.webdriver.common.keys import Keys
from proboscis import test
import unittest
driver = webdriver.Firefox()

@test(groups=["unit","login"])
class UI_test(unittest.TestCase):

    def test_SuccessfulErrorMsgOnEmptyUserName(self):
        driver.get("http://127.0.0.1:7999/login/")
        username_input = driver.find_element_by_id("id_email")
        username_input.send_keys('')
        password_input = driver.find_element_by_id("id_password")
        password_input.send_keys('bill3')
        driver.find_element_by_xpath('//input[@value = "Log In"]').click()
        driver.implicitly_wait(3)
        driver.find_element_by_class_name("error-login")

driver.close()  

def run_tests():
    from proboscis import TestProgram
   # from tests import unit

    # Run Proboscis and exit.
    TestProgram().run_and_exit()

if __name__ == '__main__':
    run_tests() 

What could be causing the BadStatusLine exception in this code?

Answer 1

Looks like a duplicate of Python/Django "BadStatusLine" error but i can't flag due to this question having a bounty. According to this answer, a BadStatusLine exception is likely caused by an empty response, as in there being no status line at all.

According to this answer, the server formally tells the client there is no more data, instead of simply causing a connection reset or rude timeout.