test_common: fix xbail for Perl 5.16

Our use of `ref' was triggering ambiguity in older versions of
the Perl parser.

Reported-by: Konstantin Ryabitsev <konstantin@linuxfoundation.org>
Link: https://public-inbox.org/meta/20210420174912.h6d2yv7zu5xr4yfc@nitro.local/

1 files changed, 1 insertions, 1 deletions

diff --git a/lib/PublicInbox/TestCommon.pm b/lib/PublicInbox/TestCommon.pm
index 2627871a..67fe6336 100644
--- a/lib/PublicInbox/TestCommon.pm
+++ b/lib/PublicInbox/TestCommon.pm
@@ -25,7 +25,7 @@ BEGIN {
         push @EXPORT, @methods;
 }
 
-sub xbail (@) { BAIL_OUT join(' ', map { ref ? (explain($_)) : ($_) } @_) }
+sub xbail (@) { BAIL_OUT join(' ', map { ref() ? (explain($_)) : ($_) } @_) }
 
 sub eml_load ($) {
         my ($path, $cb) = @_;