spawn_pp: use `which()' properly for pure-Perl spawn

I have no idea if mod_perl/mod_perl2 is used nowadays, but
we're stuck supporting it as long as mod_perl exists.  So
add some tests and make minor updates to existing ones to
ensure it stays working.

1 files changed, 4 insertions, 1 deletions

diff --git a/lib/PublicInbox/SpawnPP.pm b/lib/PublicInbox/SpawnPP.pm
index 7a5793f6..73859e9b 100644
--- a/lib/PublicInbox/SpawnPP.pm
+++ b/lib/PublicInbox/SpawnPP.pm
@@ -3,9 +3,11 @@
 
 # Pure-Perl implementation of "spawn".  This can't take advantage
 # of vfork, so no speedups under Linux for spawning from large processes.
+# Do not require this directly, only use from PublicInbox::Spawn
 package PublicInbox::SpawnPP;
 use v5.12;
 use POSIX qw(dup2 _exit setpgid :signal_h);
+use PublicInbox::Spawn qw(which);
 
 # Pure Perl implementation for folks that do not use Inline::C
 sub pi_fork_exec ($$$$$$$) {
@@ -46,7 +48,8 @@ sub pi_fork_exec ($$$$$$$) {
                 sigprocmask(SIG_SETMASK, $old) or die "SIG_SETMASK ~CHLD: $!";
                 $cmd->[0] = $f;
                 if ($ENV{MOD_PERL}) {
-                        @$cmd = (which('env'), '-i', @$env, @$cmd);
+                        $f = which('env');
+                        @$cmd = ('env', '-i', @$env, @$cmd);
                 } else {
                         %ENV = map { split(/=/, $_, 2) } @$env;
                 }