Fixing a funny bug where a object of type dave.pipeline.clipboard.Clipboard wasn't being recognised as a clipboard. The new test is watered down a little. It only tests that the output type from the wrapped function is the same as the input type.
Fixing a funny bug where a object of type dave.pipeline.clipboard.Clipboard wasn't
being recognised as a clipboard. The new test is watered down a little. It only
tests that the output type from the wrapped function is the same as the input type.

barentsen/dave,barentsen/dave,barentsen/dave,barentsen/dave