Add Change-ID to git commits so they can be accepted for review by gerrit

add-missing-change-id.pl

#!/usr/bin/env perl
# run as `git filter-branch --msg-filter /path/to/add-missing-change-id.pl [REF_SPEC]`
# where REF_SPEC is optional or something like origin/master..HEAD

use strict;
use warnings;

my $has_change_id;
while (<>) {
	$has_change_id ||= m{Change-Id:};
	print;
}

print "\nChange-Id: I$ENV{GIT_COMMIT}\n"
	unless $has_change_id;