post-receive

#!/usr/bin/perl

use strict;
use warnings;

my $headref = `git symbolic-ref HEAD`;
my $head;
unless (($head) = ($headref =~ m!^refs/heads/(.*)!)) {
    die "invalid HEAD ref '$headref'";
}

print STDERR "current branch: $head\n";

while (<>) {
    chomp;
    my ($old_ref, $new_ref, $refname) = split /\s/;

    my ($remote, $branch);
    if (($remote, $branch) = ($refname =~ m!^refs/remotes/([^/]+)/(.*)$!)) {
        if ($branch eq $head) {
            print STDERR "Merging $remote/$branch\n";
            system("git merge --ff-only $remote/$branch");
        } else {
            print STDERR "Ignoring update to $remote/$branch\n";
        }
    } else {
        warn "Invalid ref update '$refname'\n";
    }
}