Merge branch 'xx/disable-replace-when-building-midx' into jch

The procedure to build multi-pack-index got confused by the
replace-refs mechanism, which has been corrected by disabling the
latter.

* xx/disable-replace-when-building-midx:
  midx: disable replace objects

builtin/multi-pack-index.c

@@ -8,6 +8,7 @@
 #include "strbuf.h"
 #include "trace2.h"
 #include "object-store-ll.h"
+#include "replace-object.h"
 
 #define BUILTIN_MIDX_WRITE_USAGE \
 	N_("git multi-pack-index [<options>] write [--preferred-pack=<pack>]" \
@@ -273,6 +274,8 @@ int cmd_multi_pack_index(int argc, const char **argv,
 	};
 	struct option *options = parse_options_concat(builtin_multi_pack_index_options, common_opts);
 
+	disable_replace_refs();
+
 	git_config(git_default_config, NULL);
 
 	if (the_repository &&

t/t5326-multi-pack-bitmaps.sh

@@ -434,6 +434,27 @@ test_expect_success 'tagged commits are selected for bitmapping' '
 	)
 '
 
+test_expect_success 'do not follow replace objects for MIDX bitmap' '
+	rm -fr repo &&
+	git init repo &&
+	test_when_finished "rm -fr repo" &&
+	(
+		cd repo &&
+
+		test_commit A &&
+		test_commit B &&
+		git checkout --orphan=orphan A &&
+		test_commit orphan &&
+
+		git replace A HEAD &&
+		git repack -ad --write-midx --write-bitmap-index &&
+
+		# generating reachability bitmaps with replace refs
+		# enabled will result in broken clones
+		git clone --no-local --bare . clone.git
+	)
+'
+
 corrupt_file () {
 	chmod a+w "$1" &&
 	printf "bogus" | dd of="$1" bs=1 seek="12" conv=notrunc