git-ls-files(1) is plumbing command, its output will never change
regardless of configuration, version.
git-status(1) output will be changed depends on configuration.
At least, 986d4dbc7d (common/environment/setup/git.sh: ensure untracked
files are checked., 2017-11-24) was added to address a different output
on `status.showUntrackedFiles`.
By doing this, also reduce a pipe, and a fork-exec.
Technically, git-log(1) is also a porcelain, but I _think_ `%ct` is
stable enough to stay there. If the day has come, that `git-log(1)` can
be replaced with:
git cat-file commit HEAD |
sed -ne '/^committer/{s/.* \([0-9]*\) [-+][0-9][0-9][0-9][0-9]$/\1/p;q}'
fd61886616