As I was working on another project, I ran into some other project doing exactly this. Our current wire protocol is effectively "len-of-thing thing", but msgpack already includes headers in the serialization--making it an iterably consumable format. This means we don't need to use/waste bytes on the wire for the len of the string (esp. since its currently a string serialization of how many bytes).
This change simplifies the wire protocol, but still maintains flexibility for changes later-- since we are effectively just msgpacking dicts across the wire.
Note: this is a backwards incompatible wire protocol change. This is only being done as TCP is considered "experimental". This will be the last and only change to the wire protocol in a backwards incompatible fashion-- as we are working towards first-class support for the next release.
8309b69740