Normally, if the current branch is up to date, the rebase is aborted.
However, it may be desirable to allow rebasing even if the current
branch is up to date. When using the '--whitespace=fix' option -f is
implied.
Signed-off-by: Sverre Rabbelier <srabbelier@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>