Re: [PATCH] update-index: add --swap to swap index and worktree content

Jeff King [off-list ref] writes:

  # add some content with an error
  echo 'printf("hello word!\n")' >hello.c
  git add hello.c

  # work on it more, realizing the error
  echo 'printf("goodbye world!\n") >hello.c

  # now what? you want to stage the s/word/world/ fixup,
  # but you want to keep the hello/goodbye thing as a separate change.
  # Using anything line-based is going to conflate the two.
  # The change is simple, though, so you can just as easily edit the
  # index file, if only you could get to it. So you do:
  git update-index --swap hello.c
  sed -i s/word/world/ hello.c
  git update-index --swap hello.c

So the swap really functions as a toggle of "I would like to work on
the index version for a minute", and then you toggle back when you're
done.

And you have to redo what you did to the index version in the working tree
after the second "swap", no?