[RFD] git update-index --remove frotz --add frotz expected behaviour?

I'm a bit stumped by update-index' behaviour when calling --remove and --add on the same file in that order:

$ touch frotz $ git update-index --add frotz $ rm frotz $ git status -s AD frotz $ git update-index --remove frotz --add frotz $ echo $? 0 $ git status -s $

Notice that update-index doesn't complain that I'm trying to add a file that doesn't exist, and it's returning with 0.

Is this expected behaviour? Shouldn't I get some sort of error message telling me that I'm trying to add a file I've just removed? Compare:

$ touch xyzzy $ git update-index --add xyzzy $ rm xyzzy $ git update-index --remove xyzzy $ git update-index --add xyzzy error: xyzzy: does not exist and --remove not passed fatal: Unable to process path xyzzy

Can anyone explain this to me?