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

changeset:   0:9426b370c206
tag:         tip
user:        My Name <myname@example.com>
date:        Mon Jan 12 13:46:40 1970 +0000
summary:     commit-1