Use test case to detect buggy Encoder instead of fixed list of bad versions
Use test case to detect buggy Encoder instead of fixed list of bad versions

Also fixes client under Python 3.2.4+, where the work-around code
previously raised an Exception during client startup

mancoast/cado-nfs,mancoast/cado-nfs,mancoast/cado-nfs,mancoast/cado-nfs,mancoast/cado-nfs,mancoast/cado-nfs,mancoast/cado-nfs