Unexpected messages by git rebase -m

I did the usual fix-up-the-second-commit procedure, this time with 'git 
rebase -m'. The result is OK, but rebase writes something unexpected:

git init
echo a > x && git add x && git commit -m A
echo b > x && git add x && git commit -m B
echo c > x && git add x && git commit -m C
git checkout HEAD^
echo b1 > x && git add x && git commit --amend -m B1

Here we have this history:

  A--B--C  <- master
   \
    B1  <- detached HEAD

git rebase -m HEAD master
git rebase --skip	# B is in conflict; we don't need it
git checkout master x	# resolve another conflict

Now look what rebase has to say:

$ git rebase --continue 
[detached HEAD 90c7916] C
 1 files changed, 1 insertions(+), 1 deletions(-)
Committed: 0001 C
Already applied: 0002 C
All done.

Notice "Committed: 0001 C" followed by "Already applied: 0002 C". I'd expect 
only "Committed: 0002 C". What's up?

-- Hannes