This is a 3rd party source code managed on 2 branches: master and vendor. Handle new updates from the vendor, for example, as follows:

 git checkout vendor
 rm -rf *
 tar xvfz ~/Downloads/lua-2.2.tar.gz 
 mv lua-2.2/* .
 rmdir lua-2.2
 git add .
 git commit -a -m 'Vendor update. Version 2.2' # -a picks up deleted 
 git tag 'lua-2.2'
 git checkout master 
 git merge vendor
 git tag lua-2.2.0