rev-list: fix showing distance when using --bisect-all

Before d467a525 ("Make '--decorate' set an explicit 'show_decorations'
flag", Nov 3 2008), commit decorations were shown whenever they exist, and
distances stored in them by "git rev-list --bisect-all" were automatically
shown.  d467a525 changed the rule so that commit decorations are not shown
unless rev_info explicitly asks to, with its show_decorations bit, but
forgot that the ones "git rev-list --bisect-all" adds need to be shown.

This patch fixes this old breakage.
Signed-off-by: NChristian Couder <chriscool@tuxfamily.org>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

builtin-rev-list.c

@@ -608,6 +608,7 @@ int cmd_rev_list(int argc, const char **argv, const char *prefix)
 		if (!strcmp(arg, "--bisect-all")) {
 			bisect_list = 1;
 			bisect_find_all = 1;
+			revs.show_decorations = 1;
 			continue;
 		}
 		if (!strcmp(arg, "--bisect-vars")) {