jj split -i <paths> with an external merge tool includes other file into the first commit

[dotdash]

Description

When using jj split -i <paths> with an external merge tool, file that are added/change but not included in <paths> get added to the first commit. This is unexpected does not happen with the built-in editor

Steps to Reproduce the Problem

mkdir test; cd test; jj git init
echo 123 > file1; echo 456 > file2
jj commit -m init
echo 123 >> file1; echo 456 >> file2; echo xxx > file3
jj split --tool vimdiff file1
# Quit vimdiff, set split commit message etc.

Expected Behavior

The newly split commit only contains the modifications for file1.

Actual Behavior

The newly split commit contains the modifications for file1 and file2 as well as the newly added file3.

Specifications

• Platform: Linux Debian Sid
• Version: jj 0.25.0-041c4fecb77434dd6720e7d7f1ce48d9575ac5f7