When processing any errors that come out of the pysvn client, we would cast the

exception to unicode without specifying an encoding. This resulted in any utf-8

filenames or other text triggering a UnicodeDecodeError. I've changed this to

first coerce the exception to bytes, and then decode. While I was in here, I

also fixed up a duplicate cast.

Ran unit tests (this error handler is exercised in the tests).