Groupfolders 4.1.6 Released Problem

I am a little confused the relation between released version and source code for groupfolder.
I am a user for NC16, I try to explore the source code for groupfolder-4.1.6.
There is a tag “4.1.6” on GitHub . So I download it and try to build it myself. But it not work.
After reading the source code, I found that the tag is v4.1.6 but the app/info.xml point out the min-version support is NC18.
It really confuse me… Is the tag not for release?

Btw, I also open an issue with detail information. #877