The REL1_27 (and maby others) branch is pointing to version 1.2.1 instead of the newest version (1.3.0), can you please update this?
Topic on Extension talk:Widgets
1.27 is EOL. You should upgrade to the next LTS.
No chance. In the meantime this extension is completely messed up, i.e. you have to decide which version to use in connection with your version of MediaWiki. In the meantime you are better of using branches. (task T231297)