I agree that this is a bug. However, I want to point out that this usage of `Except` does not seem to be allowed in older versions.

In version 9.0:

[![enter image description here][1]][1]

We don't get the expected `True` answer.  An error message is issued.  The error message is also given for your example.

In version 10.0:

[![enter image description here][2]][2]

The error is *not* shown for your example in verson 10.0.2.

In version 10.3.1 everything works fine:

[![enter image description here][3]][3]

It seems that this usage of `Except` is new in 10.1, 10.2 or 10.3 and that the renaming rules were not yet updated to be compatible with it.  With this context, it seems like a bug.

The change is not mentioned on the documentation page of `Except`, which is annoying.

  [1]: https://i.sstatic.net/G64rL.png
  [2]: https://i.sstatic.net/eisyw.png
  [3]: https://i.sstatic.net/aGpYJ.png