[Core] Manually editing the URL alias will always update the default language

[boazpoolman]

Originally reported in #267.

When I manually edit the Australian URL to the correct value (e.g., article-one-for-at), it also automatically changes the German URL to match (article-one-for-at), which is incorrect.
The system seems not to allow saving different slugs/URLs per localization — any change affects all languages simultaneously.

[boazpoolman]

This issue was solved in version 1.4.3