Corrupts query strings with %25 → %2525 → %252525 → ⋯

[andersk]

>>> url = 'http://example.com/?q=%25'
>>> url = Url.validateUrl(url, Options())['cleanUrl']; url
'http://example.com/?q=%2525'
>>> url = Url.validateUrl(url, Options())['cleanUrl']; url
'http://example.com/?q=%252525'
>>> url = Url.validateUrl(url, Options())['cleanUrl']; url
'http://example.com/?q=%25252525'
>>> url = Url.validateUrl(url, Options())['cleanUrl']; url
'http://example.com/?q=%2525252525'