redirect_from creates duplicate locale prefixes (e.g., /de/de/...) for secondary languages

[GruberMarkus]

Hi @untra,

I think I found a bug regarding redirect_from page generation in secondary languages. It feels closely related to issue #284 and PR #293.

The problem is that redirect_from links are created perfectly for the main language, but they get broken, duplicated locale paths for secondary languages.

Reproduction Steps

File: 2026-07-03-some-title.en.md (Main Language)

---
layout: "post"
lang: "en"
locale: "en"
title: "Some English title"
description: "Some English description"
slug: "some-title"
permalink: "/blog/:year/:month/:day/:slug"
redirect_from:
  - "/blog/2025/08/11/some-title"
  - "/blog/2025/08/11/some-title/"
---

File: 2026-07-03-some-title.de.md (Secondary Language)

---
layout: "post"
lang: "de"
locale: "de"
title: "Some German title"
description: "Some German description"
slug: "some-title"
permalink: "/blog/:year/:month/:day/:slug"
redirect_from:
  - "/blog/2025/08/11/some-title"
  - "/blog/2025/08/11/some-title/"
---

Observed Behavior

• Main Language (en): Redirects are generated correctly.
  /blog/2025/08/11/some-title correctly points to /blog/2026/07/03/some-title.

• Secondary Language (de): The redirect pages are generated at the wrong file paths, duplicating the locale prefix:

  /de/de/blog/2025/08/11/some-title.html
  /de/de/blog/2025/08/11/some-title/index.html
  

  (Note: Inside these wrongly generated files, the target URL metadata actually points to the correct location: /de/blog/2026/07/03/some-title)

Scope

I am observing this faulty path generation for both posts and pages using redirect_from.

Please let me know if you need any further logs or configuration details to help track this down!

[untra]

the next release of polyglot should have the fix for this