mbox: do not try to create filename from empty string

This was causing warnings to pop up in syslogs for messages with
empty Subject headers.

2 files changed, 2 insertions, 2 deletions

diff --git a/lib/PublicInbox/Mbox.pm b/lib/PublicInbox/Mbox.pm
index 42cedd15..c50a118b 100644
--- a/lib/PublicInbox/Mbox.pm
+++ b/lib/PublicInbox/Mbox.pm
@@ -18,7 +18,7 @@ use Email::MIME::Encode;
 sub subject_fn ($) {
         my ($hdr) = @_;
         my $fn = $hdr->header('Subject');
-        return 'no-subject' unless defined($fn);
+        return 'no-subject' if (!defined($fn) || $fn eq '');
 
         # no need for full Email::MIME, here
         if ($fn =~ /=\?/) {
diff --git a/lib/PublicInbox/MboxGz.pm b/lib/PublicInbox/MboxGz.pm
index 1621cff8..ef560426 100644
--- a/lib/PublicInbox/MboxGz.pm
+++ b/lib/PublicInbox/MboxGz.pm
@@ -23,7 +23,7 @@ sub response {
         my $body = $class->new($ctx, $cb);
         # http://www.iana.org/assignments/media-types/application/gzip
         my @h = qw(Content-Type application/gzip);
-        if ($fn) {
+        if (defined $fn && $fn ne '') {
                 $fn = to_filename($fn);
                 push @h, 'Content-Disposition', "inline; filename=$fn.mbox.gz";
         }