[PATCH] spawn_pp: fix incorrect `use'

[Eric Wong]

We can't `use PublicInbox::Spawn' from SpawnPP because
PublicInbox::Spawn loads SpawnPP from BEGIN.

Fixes: 9eb8baf199cd148b (spawn_pp: use `which()' properly for pure-Perl spawn, 
2023-01-29)
---
 lib/PublicInbox/SpawnPP.pm | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/lib/PublicInbox/SpawnPP.pm b/lib/PublicInbox/SpawnPP.pm
index 73859e9b..5609f74a 100644
--- a/lib/PublicInbox/SpawnPP.pm
+++ b/lib/PublicInbox/SpawnPP.pm
@@ -7,7 +7,7 @@
 package PublicInbox::SpawnPP;
 use v5.12;
 use POSIX qw(dup2 _exit setpgid :signal_h);
-use PublicInbox::Spawn qw(which);
+# this is loaded by PublicInbox::Spawn, so we can't use/require it, here
 
 # Pure Perl implementation for folks that do not use Inline::C
 sub pi_fork_exec ($$$$$$$) {
@@ -48,7 +48,7 @@ sub pi_fork_exec ($$$$$$$) {
                sigprocmask(SIG_SETMASK, $old) or die "SIG_SETMASK ~CHLD: $!";
                $cmd->[0] = $f;
                if ($ENV{MOD_PERL}) {
-                       $f = which('env');
+                       $f = PublicInbox::Spawn::which('env');
                        @$cmd = ('env', '-i', @$env, @$cmd);
                } else {
                        %ENV = map { split(/=/, $_, 2) } @$env;