$git_midx and $self->with_umask(sub {
my @cmd = ('multi-pack-index');
push @cmd, '--no-progress' if ($opt->{quiet}//0) > 1;
+ my $lk = $self->lock_for_scope;
system('git', "--git-dir=$ALL", @cmd, 'write');
# ignore errors, fairly new command, may not exist
});