extmsg: do not modify shared array via prurl

We cannot modify elements in any shared data strucutures
shared between requests.  Oops!

1 files changed, 2 insertions, 2 deletions

diff --git a/lib/PublicInbox/ExtMsg.pm b/lib/PublicInbox/ExtMsg.pm
index 09ee8d6e..912a675d 100644
--- a/lib/PublicInbox/ExtMsg.pm
+++ b/lib/PublicInbox/ExtMsg.pm
@@ -138,8 +138,8 @@ again:
                 $code = 300;
                 $s .= "\nPerhaps try an external site:\n\n";
                 my $env = $cgi->{env};
-                foreach my $u (@EXT_URL) {
-                        $u = PublicInbox::Hval::prurl($env, $u);
+                foreach my $url (@EXT_URL) {
+                        my $u = PublicInbox::Hval::prurl($env, $url);
                         my $r = sprintf($u, $href);
                         my $t = sprintf($u, $html);
                         $s .= qq{<a\nhref="$r">$t</a>\n};