filter-github-emails: Don't create empty subject

This shouldn't happen in practice[tm], but if we receive the header
line "Subject: [monitoring-plugins] ", then we won't touch it anymore.

1 files changed, 2 insertions, 2 deletions

diff --git a/libexec/filter-github-emails b/libexec/filter-github-emails
index 326495d..5abf1b0 100755
--- a/libexec/filter-github-emails
+++ b/libexec/filter-github-emails
@@ -172,8 +172,8 @@ sub edit_header {
 
         # Strip the [monitoring-plugins] tag.
         my $subject = $header->header('Subject');
-        $subject =~ s/^\[monitoring-plugins\] //;
-        $subject =~ s/^Re: \[monitoring-plugins\] /Re: /;
+        $subject =~ s/^\[monitoring-plugins\] (.+)/$1/;
+        $subject =~ s/^Re: \[monitoring-plugins\] (.+)/Re: $1/;
         $header->header_set('Subject' => $subject);
 
         return $header;