Log Message:
py-msgpack: updated to 0.5.6

0.5.6
Fix fallback.Unpacker.feed() dropped unused data from buffer
Resurrect fallback.unpack() and _unpacker.unpack(). They were removed at 0.5.5 \ 
but it breaks backward compatibility.

0.5.5
Fix memory leak in pure Python Unpacker.feed()
Fix unpack() didn't support raw option