Make blead upstream for warnings.pm

This isn’t even a dual-life module.  Why it has its own entry I don’t
know; but in any case it has to have blead for upstream, otherwise
cmp_version.t skips it.

diff --git a/Porting/Maintainers.pl b/Porting/Maintainers.pl
index b110866..716e098 100755 (executable)
--- a/Porting/Maintainers.pl
+++ b/Porting/Maintainers.pl
@@ -2002,7 +2002,7 @@ use File::Glob qw(:case);
                  lib/warnings
                  t/lib/warnings
                 ],
-        'UPSTREAM' => undef,
+        'UPSTREAM' => 'blead',
     },
 
     'win32' => {