find_beginning_of_line didn't take into account that the
previous line might have ended with \ in which case it shouldn't
stop but continue its search.
Signed-off-by: Frank Lichtenheld <frank@lichtenheld.de> Acked-by: Johannes Schindelin <Johannes.Schindelin@gmx.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>