sequencer (rebase -i): update refs after a successful rebase
An interactive rebase operates on a detached HEAD (to keep the reflog
of the original branch relatively clean), and updates the branch only
at the end.
Now that the sequencer learns to perform interactive rebases, it also
needs to learn the trick to update the branch before removing the
directory containing the state of the interactive rebase.
We introduce a new head_ref variable in a wider scope than necessary at
the moment, to allow for a later patch that prints out "Successfully
rebased and updated <ref>".
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>