spawn: correctly handle error code

Both the C and pure Perl implementions of `pi_fork_exec'
returns `-1' on error, not `undef'.

1 files changed, 1 insertions, 1 deletions

diff --git a/lib/PublicInbox/Spawn.pm b/lib/PublicInbox/Spawn.pm
index 2d9f734c..ad6be187 100644
--- a/lib/PublicInbox/Spawn.pm
+++ b/lib/PublicInbox/Spawn.pm
@@ -210,7 +210,7 @@ sub spawn ($;$$) {
         }
         my $cd = $opts->{'-C'} // ''; # undef => NULL mapping doesn't work?
         my $pid = pi_fork_exec($redir, $f, $cmd, \@env, $rlim, $cd);
-        die "fork_exec failed: $!\n" unless defined $pid;
+        die "fork_exec failed: $!\n" unless $pid > 0;
         $pid;
 }