testcommon: spawn-aware system() and qx[] workalikes

Barely noticeable on Linux, but this gives a 1-2% speedup
on a FreeBSD 11.3 VM and lets us use built-in redirects
rather than relying on /bin/sh.

1 files changed, 1 insertions, 1 deletions

diff --git a/t/config.t b/t/config.t
index 0db12359..1f50bb86 100644
--- a/t/config.t
+++ b/t/config.t
@@ -11,7 +11,7 @@ my ($tmpdir, $for_destroy) = tmpdir();
 {
         PublicInbox::Import::init_bare($tmpdir);
         my @cmd = ('git', "--git-dir=$tmpdir", qw(config foo.bar), "hi\nhi");
-        is(system(@cmd), 0, "set config");
+        is(xsys(@cmd), 0, "set config");
 
         my $tmp = PublicInbox::Config->new("$tmpdir/config");