date.formats are reported as having broken data

[digitalfrost]

thor locales:test some_locale

wrongly reports

The following keys have broken data:
date.formats.default
date.formats.long
date.formats.short

I have checked zh-CN and fr locales the error is given when the keys are clearly not broken.

Testing the en locale also reports these keys as having broken data.

[digitalfrost]

Impacts #577 #1011 since locales:complete locale is based on the same KeyStructure.check function being used by locales:test

[jlduran]

Fixed by #1087.