Trying to split repository

Hello,

One of my repositories has grown a subdirectory that I'd like to split off, so other can use it as a subproject. With the help of google, I found this solution:

    # first extract the library from the original repository
    #
    git clone --no-hardlinks repository library.tmp
    (
        cd library.tmp
        git filter-branch --subdirectory-filter CF -- --all
        git reset --hard
        git gc --aggressive
        git prune
        git gc
        git clone --bare . ../library
    )
    rm -rf library.tmp

    # Now remove the library from the original repository, so it can be
    # included as a subproject
    #
    git clone --no-hardlinks repository repository.new.tmp
    (
        cd repository.new.tmp
        git filter-branch \
            --index-filter "git rm -r -f --cached --ignore-unmatch CF" \
            -- --all
        git reset --hard
        git gc --aggressive
        git prune
        git gc
        git clone --bare . ../repository.new
    )
    rm -rf repository.new.tmp

This works fine. But there's one problem, though. "gitk --all" in the new repository still shows all the history of the removed library. The patch show no modifications, but the log entry is still there.

Any hints how to get rid of those log entries?