contrib/wix/defines.wxi

revlog: fix pure python slicing test when chain contains nullrev

The revlog mock used in the test was not behaving the same as its C counterpart.

<Include>

  <?if $(var.Platform) = "x64" ?>
    <?define IsX64 = yes ?>
  <?else?>
    <?define IsX64 = no ?>
  <?endif?>

</Include>