What happens?:
======================================================================
ERROR: test_standard_version_sites (tests.site_detect_tests.MediaWikiSiteTestCase.test_standard_version_sites) (url='www.proofwiki.org')
Test detection of standard MediaWiki sites.
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Traceback (most recent call last):
File "/home/runner/work/pywikibot/pywikibot/tests/site_detect_tests.py", line 112, in test_standard_version_sites
self.assertSite(url)
File "/home/runner/work/pywikibot/pywikibot/tests/site_detect_tests.py", line 36, in assertSite
self.assertIsInstance(MWSite(url), MWSite)
^^^^^^^^^^^
File "/home/runner/work/pywikibot/pywikibot/pywikibot/site_detect.py", line 82, in __init__
raise RuntimeError(f'Unsupported url: {self.fromurl}')
RuntimeError: Unsupported url: https://www.proofwiki.org/wiki/The test does not fail on appveyor of if running locally
Other information (browser name/version, screenshots, etc.):
See also T175584, T162991, T134647