feed: comment about the %deleted hash

It's strictly not necessary anymore since
commit fa6168c56bdd1cece178b6b852a9b2cba6ce6ffb
("feed: message must exist in current HEAD to show up")

However it can still save us some unnecessary syscalls and
round-trips to the "git cat-file --batch" process, so it's probably
worth th cost of stuffing it in a hash.

diff --git a/lib/PublicInbox/Feed.pm b/lib/PublicInbox/Feed.pm
index 3b2b7af9c9f1e26c4e4390341f3b3516da1c5125..a8578e760fdf8cc002e8ad53d9a008879ee4bff0 100644 (file)
--- a/lib/PublicInbox/Feed.pm
+++ b/lib/PublicInbox/Feed.pm
@@ -156,7 +156,7 @@ sub each_recent_blob {
 
        my $pid = open(my $log, '-|', @cmd) or
                die('open `'.join(' ', @cmd) . " pipe failed: $!\n");
-       my %deleted;
+       my %deleted; # only an optimization at this point
        my $last;
        my $nr = 0;
        my @commits = ();