If writing or committing the new index file fails, we print "Could not
write new index file." followed by "Could not reset index file to
revision $rev.". The first message seems to imply the second, so print
only the first message.
Signed-off-by: Martin von Zweigbergk <martinvonz@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>