Fixed an exception in notify extension (b2a_hex argument incorrect) Detailed messages was - incoming.notify hook raised an exception: b2a_hex() argument 1 must be string or read-only character buffer, not stringio

# should print nothing
# should print ? b/x
? b/x
# should print A b/x
A b/x
# should forget b/x
forgetting b/x
# should print nothing