[PATCH 5/9] test_common: handle '-C' (chdir) spawn option properly

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

We use it in t/lei-q-save.t, and were inadvertently writing
to the worktree.
---
 lib/PublicInbox/TestCommon.pm | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/lib/PublicInbox/TestCommon.pm b/lib/PublicInbox/TestCommon.pm
index d506e4b5..465d4b9d 100644
--- a/lib/PublicInbox/TestCommon.pm
+++ b/lib/PublicInbox/TestCommon.pm
@@ -288,6 +288,7 @@ sub run_script ($;$$) {
 	}
 	if ($run_mode == 0) {
 		# spawn an independent new process, like real-world use cases:
+		$spawn_opt->{$_} = $opt->{$_} for (qw(-C));
 		require PublicInbox::Spawn;
 		my $cmd = [ key2script($key), @argv ];
 		my $pid = PublicInbox::Spawn::spawn($cmd, $env, $spawn_opt);
@@ -302,8 +303,14 @@ sub run_script ($;$$) {
 		local %SIG = %SIG;
 		local $0 = join(' ', @$cmd);
 		my $orig_io = _prepare_redirects($fhref);
+		my $cwdfh;
+		if (my $d = $opt->{'-C'}) {
+			opendir $cwdfh, '.' or die "opendir .: $!";
+			chdir $d or die "chdir $d: $!";
+		}
 		_run_sub($sub, $key, \@argv);
 		eval { PublicInbox::Inbox::cleanup_task() };
+		die "chdir(restore): $!" if $cwdfh && !chdir($cwdfh);
 		_undo_redirects($orig_io);
 		select STDOUT;
 	}