lei_mirror: set {head} from manifest

We handle symbolic refs properly, at least.  It's also possible
for $GIT_DIR/HEAD to contain a full SHA-1/SHA-256, and we'll
support that by using update-ref --no-deref

1 files changed, 17 insertions, 0 deletions

diff --git a/lib/PublicInbox/LeiMirror.pm b/lib/PublicInbox/LeiMirror.pm
index f7db5a49..fc5bc88d 100644
--- a/lib/PublicInbox/LeiMirror.pm
+++ b/lib/PublicInbox/LeiMirror.pm
@@ -678,6 +678,23 @@ sub update_ent {
                 my $done = PublicInbox::OnDestroy->new($$, \&up_fp_done, $self);
                 start_cmd($self, $cmd, $opt, $done);
         }
+
+        $new = $self->{-ent}->{head};
+        $cur = $self->{-local_manifest}->{$key}->{head} // "\0";
+        if (defined($new) && $new ne $cur) {
+                # n.b. grokmirror writes raw contents to $dst/HEAD w/o locking
+                my $cmd = [ 'git', "--git-dir=$dst" ];
+                if ($new =~ s/\Aref: //) {
+                        push @$cmd, qw(symbolic-ref HEAD), $new;
+                } elsif ($new =~ /\A[a-f0-9]{40,}\z/) {
+                        push @$cmd, qw(update-ref --no-deref HEAD), $new;
+                } else {
+                        undef $cmd;
+                        warn "W: $key: {head} => `$new' not understood\n";
+                }
+                start_cmd($self, $cmd, { 2 => $self->{lei}->{2} }) if $cmd;
+        }
+
         $new = $self->{-ent}->{owner} // return;
         $cur = $self->{-local_manifest}->{$key}->{owner} // "\0";
         return if $cur eq $new;