thoughtbot/shoulda-matchers — pull request #571 by mcmire (2014-08-14 18:56:43+00:00)
Title: Tweak warning to be descriptive, not prescriptive

This is a fix for #569.

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While we do advise against using the validates_inclusion_of or
validates_format_of validations with boolean columns, we won't judge
if you would like to do so.