Re: [PATCH] diff: report bogus input to -C/-M/-B

Jeff King wrote:

Before:

  $ git diff -CM
  $ echo $?
  128

After:

  $ git diff -CM
  error: invalid argument to -C: M
  $ echo $?
  128

Yes, please.

Who is it that exits(128) in this code path?  Are there other
functions it calls that might return an error without reporting it to
stderr?