Add test for #126935

Author: lizmat

S32-io/io-path.t

@@ -1,7 +1,7 @@
 use v6;
 use Test;
 
-plan 15;
+plan 16;
 
 # L<S32::IO/IO::Path>
 
@@ -49,3 +49,9 @@ isa-ok $path.IO,   IO::Path, 'IO::Path.IO returns IO::Path';
       is "/".IO.cleanup, "/", "POSIX OS loaded (forward slash)"
   }
 }
+
+# RT #126935
+{
+    my $perl = "/foo|\\bar".IO.perl;
+    is $perl.EVAL.perl, $perl, "does $perl roundtrip?";
+}