The `Xorg.find_versions` method was recently updated to replace
`match_data[:content].blank?` with `match_data[:content].empty?` but
this is producing an `undefined method 'empty?' for nil` error, as
`:content` is not present when `PageMatch.find_versions` uses cached
content. This updates `Xorg.find_versions` to handle nil `:content`
values in a way that's similar to other `find_versions` methods.
67c333ec0a