The location of the pre-commit the file in INSTALL file is incorrect for proper installation. So after following the installation instructions, pre-commit is added to the .git/hooks folder, yet it is an empty file (0 byte).

That's because GitHub changed the URL for user-generated content from raw.github.com to raw.githubusercontent.com. Thus curl https://raw.github.com/hybridgroup/GitHub-Wikifier/master/pre-commit results in redirection and the pre-commit becomes an empty file.

So this

https://raw.github.com/hybridgroup/GitHub-Wikifier/master/pre-commit 

should be changed to

https://raw.githubusercontent.com/hybridgroup/GitHub-Wikifier/master/pre-commit 

So if I do,

curl https://raw.githubusercontent.com/hybridgroup/GitHub-Wikifier/master/pre-commit > .git/hooks/pre-commit;

it works.