`Integer#chr` performs some validation that we don't want/need. Octal escapes can go above 255, where it will then raise trying to convert.
`append_as_bytes` actually allows to pass a number, so we can just skip that call.
Although, on older rubies of course we still need to handle this in the polyfill.
I don't really like using `pack` but don't know of another way to do so.
For the utf-8 escapes, this is not an issue. Invalid utf-8 in these is simply a syntax error.
161c606b1f
1. The string starts out as binary
2. `ち` is appended, forcing it back into utf-8
3. Some invalid byte sequences are tried to append
> incompatible character encodings: UTF-8 and BINARY (ASCII-8BIT)
This makes use of my wish to use `append_as_bytes`. Unfortunatly that method is rather new
so it needs a fallback
e31e94a775
