[PATCH] lei_to_mail: improve SIGPIPE handling

[Eric Wong <e@80x24.org>]

I can't reproduce this in t/lei-sigpipe.t with GIANT_INBOX_DIR.
In real-world usage, having a large `lei q -f text ...' output
piped to a pager and killing the pager prematurely could
trigger:

	non-fatal error from PublicInbox::LeiToMail $?=256

messages in my terminal.  This is because $self->{lei} was
becoming undefined in the process cleanup process of
git_to_mail.  So flip the cleanup logic around and
unconditionally check for Git::cleanup state to bail out
early.

With this change, the `non-fatal error ...' message no longer
appears when I stop reading results early.
---
 lib/PublicInbox/LeiToMail.pm | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/lib/PublicInbox/LeiToMail.pm b/lib/PublicInbox/LeiToMail.pm
index 008da52e..9197bb44 100644
--- a/lib/PublicInbox/LeiToMail.pm
+++ b/lib/PublicInbox/LeiToMail.pm
@@ -136,11 +136,9 @@ sub eml2mboxcl2 {
 sub git_to_mail { # git->cat_async callback
 	my ($bref, $oid, $type, $size, $smsg) = @_;
 	$type // return; # called by PublicInbox::Git::close
-	my $self = delete $smsg->{l2m};
-	if (!defined($self)) {
-		return if $PublicInbox::Git::in_cleanup;
-		croak "BUG: no l2m (type=$type)";
-	}
+	return if $PublicInbox::Git::in_cleanup;
+	my $self = delete $smsg->{l2m} // croak "BUG: no l2m (type=$type)";
+	$self->{lei} // croak "BUG: no {lei} (type=$type)";
 	eval {
 		if ($type eq 'missing' &&
 			  ($bref = $self->{-lms_rw}->local_blob($oid, 1))) {