Cyrillic tags stopped working in 4.0.2

Cyrillic tags stopped working on my blog. They surely did in April, where I wrote the latest post: http://konakov.biz/tags/основы/ (visible in the browser as http://konakov.biz/tags/основы/). Latin tags work fine.

Expected behaviour

Blog renders Cyrillic tags like http://konakov.biz/tags/основы/

Actual behaviour

Blog renders every Cyrillic tag as http://konakov.biz/tags/.html

Steps to reproduce the problem

https://github.com/konakov/blog

Additional information

I fixed the problem by downgrading middleman-blog gem to version 4.0.1.

• Ruby version: 2.4.2
• Middleman version: 4.2.1
• Middleman Blog version: 4.0.2
• OS version: Arch Linux current stable

Problem in Middleman::Blog::UriTemplates.safe_parameterize

2.4.1 :008 > Middleman::Blog::UriTemplates.safe_parameterize('link string') => "link-string" 2.4.1 :004 > Middleman::Blog::UriTemplates.safe_parameterize('основы') => ""

Should be fixed in 4.0.3