midx.c: avoid cruft packs with repack --batch-size=0

The `repack` sub-command of the `git multi-pack-index` builtin creates a
new pack aggregating smaller packs contained in the MIDX up to some
given `--batch-size`.

When `--batch-size=0`, this instructs the MIDX builtin to repack
everything contained in the MIDX into a single pack.

In similar spirit as a previous commit, it is undesirable to repack the
contents of a cruft pack in this step. Teach `repack` to ignore any
cruft pack(s) when `--batch-size=0` for the same reason(s).

(The case of a non-zero `--batch-size` will be handled in a subsequent
commit).

Signed-off-by: Taylor Blau <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: ttaylorr

midx.c

@@ -1895,6 +1895,8 @@ static int fill_included_packs_all(struct repository *r,
 			continue;
 		if (!pack_kept_objects && m->packs[i]->pack_keep)
 			continue;
+		if (m->packs[i]->is_cruft)
+			continue;
 
 		include_pack[i] = 1;
 		count++;

t/t5319-multi-pack-index.sh

@@ -784,6 +784,29 @@ test_expect_success 'repack creates a new pack' '
 	)
 '
 
+test_expect_success 'repack (all) ignores cruft pack' '
+	git init repo &&
+	test_when_finished "rm -fr repo" &&
+	(
+		cd repo &&
+
+		test_commit base &&
+		test_commit --no-tag unreachable &&
+
+		git reset --hard base &&
+		git reflog expire --all --expire=all &&
+		git repack --cruft -d &&
+
+		git multi-pack-index write &&
+
+		find $objdir/pack | sort >before &&
+		git multi-pack-index repack --batch-size=0 &&
+		find $objdir/pack | sort >after &&
+
+		test_cmp before after
+	)
+'
+
 test_expect_success 'expire removes repacked packs' '
 	(
 		cd dup &&