repack: simplify handling of --write-bitmap-index

We previously needed to pass --no-write-bitmap-index
explicitly to pack-objects to override its reading of
pack.writebitmaps from the config. Now that it no longer
does so, we can assume that bitmaps are off by default, and
only turn them on when necessary. This also lets us avoid a
confusing tri-state flag for write_bitmaps.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/repack.c

@@ -10,7 +10,7 @@
 
 static int delta_base_offset = 1;
 static int pack_kept_objects = -1;
-static int write_bitmaps = -1;
+static int write_bitmaps;
 static char *packdir, *packtmp;
 
 static const char *const git_repack_usage[] = {
@@ -195,7 +195,7 @@ int cmd_repack(int argc, const char **argv, const char *prefix)
 				git_repack_usage, 0);
 
 	if (pack_kept_objects < 0)
-		pack_kept_objects = write_bitmaps > 0;
+		pack_kept_objects = write_bitmaps;
 
 	packdir = mkpathdup("%s/pack", get_object_directory());
 	packtmp = mkpathdup("%s/.tmp-%d-pack", packdir, (int)getpid());
@@ -221,9 +221,8 @@ int cmd_repack(int argc, const char **argv, const char *prefix)
 		argv_array_pushf(&cmd_args, "--no-reuse-delta");
 	if (no_reuse_object)
 		argv_array_pushf(&cmd_args, "--no-reuse-object");
-	if (write_bitmaps >= 0)
-		argv_array_pushf(&cmd_args, "--%swrite-bitmap-index",
-				 write_bitmaps ? "" : "no-");
+	if (write_bitmaps)
+		argv_array_push(&cmd_args, "--write-bitmap-index");
 
 	if (pack_everything & ALL_INTO_ONE) {
 		get_non_kept_pack_filenames(&existing_packs);