process_pipe: warn hackers off using it for bidirectional pipes

While most uses of ->DESTROY happens in a predictable order in
long-lived daemons, process teardown on exit is chaotic and not
subject to ordering guarantees, so we must keep both ends of a
`git cat-file --batch*' pipe at the same level in the object
hierarchy.

Drop an old Carp import while I'm in the area.

1 files changed, 1 insertions, 0 deletions

diff --git a/lib/PublicInbox/Git.pm b/lib/PublicInbox/Git.pm
index ff3ac40f..a3813bf2 100644
--- a/lib/PublicInbox/Git.pm
+++ b/lib/PublicInbox/Git.pm
@@ -156,6 +156,7 @@ sub _bidi_pipe {
                 $self->{$err} = $fh;
                 $rdr->{2} = $fh;
         }
+        # see lib/PublicInbox/ProcessPipe.pm for why we don't use that here
         my ($in_r, $p) = popen_rd(\@cmd, undef, $rdr);
         awaitpid($self->{$pid} = $p, undef);
         $self->{"$pid.owner"} = $$;