delayer: Handle drained queue properly

If the queue runs empty, there are several warnings about uninitialized
values.  Rewrite the queue handling to avoid duplicate checks.

Thanks to Christoph Biedl for the patch.

backends/delayer.in

@@ -73,18 +73,16 @@ while (1) {
         push(@queue, "$exp:$line");
     }
 
-    if ($#queue < 0) {
-        undef $timeout;
-        next;
-    }
-
-    my ($first, $line) = split(/:/, $queue[0], 2);
-    while ($#queue >= 0 && $first <= $now) {
+    undef $timeout;
+    while (@queue) {
+        my ($first, $line) = split(/:/, $queue[0], 2);
+        if ($first > $now) {
+            $timeout = $first - $now;
+            last;
+        }
         print OUT $line;
         shift(@queue);
-        ($first, $line) = split(/:/, $queue[0], 2);
     }
-    $timeout = $first - $now;
 }
 
 __END__
@@ -244,9 +242,9 @@ with some I<args> parameters.
 
 =head1 BUGS
 
-If the standard input is closed (when for instance the feed is closed), all
-lines in the store are printed immediately, breaking the contract of delaying
-them, unless the B<--store> option is used.
+If the standard input is closed (when for instance the feed is closed or
+restarted), all lines in the store are printed immediately, breaking the
+contract of delaying them, unless the B<--store> option is used.
 
 If the number of articles in that feed is rather low (just a few articles per
 delay time or less), some effects of buffering will delay the transmission