[MRG+1] PEP8 ofsite middleware

[stav]

No description provided.

[kmike]

Looks good, thanks @stav!
//cc @dangra - do you have any idea why is AppVeyor failing?

[dangra]

no idea yet

FTR

================================== FAILURES ===================================
____________ CrawlerRunnerTestCase.test_spidermanager_deprecation _____________
self = <tests.test_crawler.CrawlerRunnerTestCase testMethod=test_spidermanager_deprecation>
    def test_spidermanager_deprecation(self):
        with warnings.catch_warnings(record=True) as w:
            runner = CrawlerRunner({
                'SPIDER_MANAGER_CLASS': 'tests.test_crawler.CustomSpiderLoader'
            })
            self.assertIsInstance(runner.spider_loader, CustomSpiderLoader)
>           self.assertEqual(len(w), 1)
C:\projects\scrapy\tests\test_crawler.py:177: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
c:\projects\scrapy\.tox\py36\lib\site-packages\twisted\trial\_synctest.py:432: in assertEqual
    super(_Assertions, self).assertEqual(first, second, msg)
E   twisted.trial.unittest.FailTest: 3 != 1

[dangra]

and restarting the build "fixed" it 😕