[xmlsec] Bug in bn.c ?

[xs04.jmdesp at free.fr]

I apparently found a bug in bn.c, but I'm very surprised it would not have come
out earlier.

At line 300, the code :
    /* we might have '0' at the beggining, remove it */
    for(len = i; (len > 0) && (res[len - 1] == '0'); len--);
        res[len] = '\0';

apparently will result in an empty content if the string is all zero.

In my test, this corrects it, and leaves at least one zero :
    for(len = i; (len > 1) && (res[len - 1] == '0'); len--);
        res[len] = '\0';