exec git init
exec git config user.email i@example.com
exec git config user.name someone
exec git checkout -b main

exec git add file
exec git commit -m 'commit'
exec sed -i '1d' file
exec git add file
exec sed -i '1 i\line1' file

exec git status --porcelain --branch
stdout '## main\nMM file'

env WANT_STATUS='NumModified=1 NumStaged=1 LocalBranch=main HEAD=[a-f0-9]{7} State=Default Insertions=1'
gitstatus
! stderr .

-- file --
line1
line2