commit 66e3a255147d1714f313399bfdfb52fff8afbf50
Author: relan <relan@users.noreply.github.com>
Date:   Sat Mar 7 09:13:48 2020 +0300

    Validate UTF-8 byte sequence.
    
    The 2nd and subsequent bytes in a UTF-8 byte sequence must look like
    10xxxxxx. The missing checks could lead to crash later.
