The time_notes script, which uses POSIX shell features, is
currently sometimes run with a non-POSIX /bin/sh.
Reported-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Signed-off-by: Jonathan Nieder <jrnieder@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>