XSConfig.t checks for XS and non-XS Config.pm to match exactly.
However, the script that makes the XS version (ext/Config/Config_xs.PL)
is not meant to do exactly translation. It only writes keys expected
for this particular perl version.

Multi-version support in perl-cross does sometimes generate keys
not meant for the perl version being compiled. This is probably
harmless, and definitely much easier to support, so we relax the
test to allow extra keys in non-XS module.

XS module in never used at build time with perl-cross.

--- a/ext/Config/t/XSConfig.t
+++ b/ext/Config/t/XSConfig.t
@@ -52,7 +52,7 @@
 Config->import();
 require 'Config_heavy.pl';
 require Test::More;
-Test::More->import (tests => 4);
+Test::More->import (tests => 3);
 
 ok(isXSUB($cv), 'XS Config:: is XS');
 
@@ -187,12 +187,17 @@
   for my $k (@cannedkeys) {
     $Config_copy{$k} = '' unless exists $Config{$k};
   }
-  is (scalar keys %Config_copy, $klenXS, 'same adjusted key count');
-} else {
-  is (scalar(keys %Config), $klenXS, 'same key count');
 }
 
-is_deeply ($copy ? \%Config_copy : \%Config, \%XSConfig, "cmp PP to XS hashes");
+$Config = $copy ? \%Config_copy : \%Config;
+
+# Non-XS config *may* contain additional keys in perl-cross.
+# Remove them to avoid false positives with is_deeply.
+foreach(keys %$Config) {
+	delete $Config->{$_} unless exists $XSConfig{$_};
+}
+
+is_deeply ($Config, \%XSConfig, "cmp PP to XS hashes");
 
 # old Test::Builders dont have is_passing
 if ( Test::More->builder->can('is_passing')