Fix byte2int for array multiple indices

[u1735067]

# py -3
>>> t
b'test'
>>> t[0]
116
>>> t[0:1]
b't'
>>> byte2int(t[0:1])
b't'

-> byte2int isn't working when extracting from "array" using 2 indices.
So let's simply check if it's already an int or not.

[dahu33]

+1 can someone review/merge this one?

[dainnilsson]

I don't really think this is a bug, it seems to me that the function does as it is named, IE it takes a single byte, and returns an int. What would be the point of using it with multiple indexes, if the only valid "second index" is the first index + 1? I'd rather consider the byte2int(x[i:i+1]) usage to be invalid (so the bug is rather in how python-u2flib-host calls the function). Does that make sense? Have I overlooked anything?

[u1735067]

IE it takes a single byte, and returns an int

>>> t[0:1]
b't'
>>> byte2int(t[0:1])
b't'

Nop (but with Yubico/python-u2flib-host@bdeac17 I agree it should not cause trouble anymore)

[dainnilsson]

By "takes a single byte" I mean "what you get when you index a value in a "bytes" object". When you slice a "bytes", you get a new "bytes", even if the length happens to be 1.