Bencode_streaming.Encode fails on min_int

[stedolan]

# Bencode_streaming.Encode.to_string (Bencode.Integer min_int);;
Exception: Invalid_argument "String.blit / Bytes.blit_string".

(seems to be just Bencode_streaming, Bencode.encode_to_string works fine)

[c-cube]

Interesting. Because - min_int is min_int, the log10 of - min_int is negative and leads to a wrong estimation of the length it will take once displayed.