Revert "[bugfix] Don't expect default Site is in random sample"
Revert "[bugfix] Don't expect default Site is in random sample"

This reverts commit 106291f8dfa19d19d6c823bb83787e47e404e938.

Change-Id: I7c6b15d8090e0b88f21b75af4bcb1b927f25e520

wikimedia/pywikibot-core,PersianWikipedia/pywikibot-core,wikimedia/pywikibot-core