view: do not recompress already-compressed MID for anchors

This is merely for display, so on the off chance somebody does
send a 40-byte MID with nothing but hexadecimal characters,
the worst that could happen is we repeat an anchor name in the
rendered HTML.  This has no impact on git archival or Xapian
indexing.

1 files changed, 5 insertions, 1 deletions

diff --git a/lib/PublicInbox/View.pm b/lib/PublicInbox/View.pm
index e7ca73dc..6fbc3660 100644
--- a/lib/PublicInbox/View.pm
+++ b/lib/PublicInbox/View.pm
@@ -477,7 +477,11 @@ sub linkify_refs {
 
 sub anchor_for {
         my ($msgid) = @_;
-        'm' . mid_compressed(mid_clean($msgid), 1);
+        my $id = $msgid;
+        if ($id !~ /\A[a-f0-9]{40}\z/) {
+                $id = mid_compressed(mid_clean($id), 1);
+        }
+        'm' . $id;
 }
 
 sub simple_dump {