This experimentally fixes issue 456, but I'm no expert on the Marshal format. I also don't know if the test is in the right directory or if checking in a small binary file (the marshal data) is a good idea or not.
Support marshaling and unmarshaling strings with repeated encodings
When an encoding other than UTF-8 or US-ASCII is used, the encoding is
marshaled as a String, which means that the value can be reused via
the `LINK` type.
I cherry-picked this. Thanks jiggly puff-like entity.