fzf-git-add outputs incorrect paths

[popstas]

Widget outputs paths like:

 MtREADME.md
??tzsh.yml

If i replace

git status --porcelain | \
  sed "s/^\(..\) /\1\t${base_path}/" | \
  grep "^.[MD?]" | \
  selector-select -m

to

git status --porcelain | \
  grep "^.[MD?]" | \
  cut -c 4- | \
  selector-select -m

Script output paths correct.

But I cannot understand purpose of $base_path.