sequencer: fix missing newline

When using rebase --interactive where one of the lines is marked as
'edit' this is the resulting output:

    Stopped at ec3b9c4...  stuffYou can amend the commit now, with

      git commit --amend

    Once you are satisfied with your changes, run

      git rebase --continue

A newline character is missing at the end of the "Stopped at ..." line and
before the "You can amend ..." line.  This patch fixes the malformed output by
adding the missing newline character to the end of the "Stopped at ..." line.

Signed-off-by: Brandon Williams <bmwill@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
