Whoops, it extracted the newest row :) Correction:

    git ls-files -z|xargs -0 -n 1 git blame --date=format:%Y%m%d -f |grep -Eo '\d{8}.*' |sort -n | head -n 1 | sed 's/^[^)]*)*[ \t]//'

This also use a null delimiter for the files and fixes a small sed pattern bug.