Merge branch 'js/add-i-delete'

Rewrite of "git add -i" in C that appeared in Git 2.25 didn't
correctly record a removed file to the index, which was fixed.

* js/add-i-delete:
  add --interactive: allow `update` to stage deleted files

diff --cc add-interactive.c
Simple merge

diff --cc t/t3701-add-interactive.sh
Simple merge