pack-objects: fix --no-keep-true-parents

Since 99fb6e04cb (pack-objects: convert to use parse_options(),
2012-02-01) git pack-objects has accepted --no-keep-true-parents, but
this option does the same as --keep-true-parents.  That's because it's
defined using OPT_SET_INT with a value of 0, which sets 0 when negated
as well.

Turn --no-keep-true-parents into the opposite of --keep-true-parents by
using OPT_BOOL and storing the option's status directly in a variable
named "grafts_keep_true_parents" instead of in negative form in
"grafts_replace_parents".

Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/builtin/pack-objects.c b/builtin/pack-objects.c
index 9cfc880..193bb0b 100644
--- a/builtin/pack-objects.c
+++ b/builtin/pack-objects.c
@@ -4256,8 +4256,8 @@ int cmd_pack_objects(int argc, const char **argv, const char *prefix)
 				N_("ignore this pack")),
 		OPT_INTEGER(0, "compression", &pack_compression_level,
 			    N_("pack compression level")),
-		OPT_SET_INT(0, "keep-true-parents", &grafts_replace_parents,
-			    N_("do not hide commits by grafts"), 0),
+		OPT_BOOL(0, "keep-true-parents", &grafts_keep_true_parents,
+			 N_("do not hide commits by grafts")),
 		OPT_BOOL(0, "use-bitmap-index", &use_bitmap_index,
 			 N_("use a bitmap index if available to speed up counting objects")),
 		OPT_SET_INT(0, "write-bitmap-index", &write_bitmap_index,