apply-one-time-sed.sh: modernize style
Convert `[ ... ]` to use `test` and test for the existence of a regular
file (`-f`) instead of any file (`-e`).
Move the `then`s onto their own lines so that it conforms with the
general test style.
Instead of redirecting input into sed, allow it to open its own input.
Use `cmp -s` instead of `diff` since we only care about whether the two
files are equal and `diff` is overkill for this.
Signed-off-by: Denton Liu <liu.denton@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>