builtin/maintenance: fix loose objects task emitting pack hash

The "loose-objects" maintenance tasks executes git-pack-objects(1) to
pack all loose objects into a new packfile. This command ends up
printing the hash of the packfile to stdout though, which clutters the
output of `git maintenance run`.

Fix this issue by disabling stdout of the child process.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: pks-t

builtin/gc.c

@@ -1159,6 +1159,12 @@ static int pack_loose(struct maintenance_run_opts *opts)
 
 	pack_proc.in = -1;
 
+	/*
+	 * git-pack-objects(1) ends up writing the pack hash to stdout, which
+	 * we do not care for.
+	 */
+	pack_proc.out = -1;
+
 	if (start_command(&pack_proc)) {
 		error(_("failed to start 'git pack-objects' process"));
 		return 1;

t/t7900-maintenance.sh

@@ -975,4 +975,20 @@ test_expect_success '--detach causes maintenance to run in background' '
 	)
 '
 
+test_expect_success 'repacking loose objects is quiet' '
+	test_when_finished "rm -rf repo" &&
+	git init repo &&
+	(
+		cd repo &&
+
+		test_commit something &&
+		git config set maintenance.gc.enabled false &&
+		git config set maintenance.loose-objects.enabled true &&
+		git config set maintenance.loose-objects.auto 1 &&
+
+		git maintenance run --quiet >out 2>&1 &&
+		test_must_be_empty out
+	)
+'
+
 test_done