inbox: cloneurl: avoid undef to hash table value

This saves us some memory for the hash slot in the common case
the `cloneurl' file doesn't exist.

1 files changed, 3 insertions, 3 deletions

diff --git a/lib/PublicInbox/Inbox.pm b/lib/PublicInbox/Inbox.pm
index 3ba92c99..1d5fc708 100644
--- a/lib/PublicInbox/Inbox.pm
+++ b/lib/PublicInbox/Inbox.pm
@@ -216,11 +216,11 @@ sub description {
 
 sub cloneurl {
         my ($self) = @_;
-        ($self->{cloneurl} //= do {
+        $self->{cloneurl} // do {
                 my $s = try_cat("$self->{inboxdir}/cloneurl");
                 my @urls = split(/\s+/s, $s);
-                scalar(@urls) ? \@urls : undef
-        }) // [];
+                scalar(@urls) ? ($self->{cloneurl} = \@urls) : undef;
+        } // [];
 }
 
 sub base_url {