t6050: add tests for listing with --format This patch adds tests for "git replace -l --format=<fmt>". 'short', 'medium' and 'full' are the only allowed values for <fmt>. 'short' is the same as with no --format option. Tests for 'medium' and 'full' are the most needed. Signed-off-by: Christian Couder <chriscool@tuxfamily.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>