symtable is useful when combined with compile() to AST to understand what the names bind to.  But symtable.symtable() doesn't accept a bytes object, while compile does.  Ultimately these feed down to the same API, and could easily lead to subtle mismatches due to encodings. 

The workaround seems to be to use the tokenize.detect_encoding to discover the encoding and then do the encoding from Python, but this seems wasteful.