[PATCH] t/spawn: fix with unusual env locations

[Alyssa Ross <hi@alyssa.is>]

The call to spawn clears the environment, including PATH.  This means
that an env in a non-default location wouldn't be found, while all the
other tests work because they use PATH.  We can fix this by looking up
which PATH to use beforehand.

I ran into this when packaging public-inbox for Nixpkgs.  We build in
a chroot, and in this case the env I wanted to use was at
/nix/store/7rmjki86923bw1inx0czpp4wgy0kk687-coreutils-8.31/bin/env.
---
 t/spawn.t | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/t/spawn.t b/t/spawn.t
index aba1a26..5549ca8 100644
--- a/t/spawn.t
+++ b/t/spawn.t
@@ -41,7 +41,8 @@ use PublicInbox::Spawn qw(which spawn popen_rd);
 {
 	my ($r, $w);
 	pipe $r, $w or die "pipe failed: $!";
-	my $pid = spawn(['env'], {}, { -env => 1, 1 => fileno($w) });
+	my $env = which('env');
+	my $pid = spawn([$env], {}, { -env => 1, 1 => fileno($w) });
 	close $w or die "close pipe[1] failed: $!";
 	ok(!defined(<$r>), 'read stdout of spawned from pipe');
 	is(waitpid($pid, 0), $pid, 'waitpid succeeds on spawned process');
-- 
2.22.1