Do not play with mutable data

[nogenhat]

There can be issues, when you force encode original string into binary and then someone else want to use this string.

[fl00r]

I believe the problem is here

beefcake/lib/beefcake/buffer/encode.rb

Line 107 in 71b06dc

def append_string(s)

[bkerley]

Is there a way to write a test for this?

[bkerley]

This is closely related to but distinct from #69 and #70 .

That is all :)