I accidently built libssh.so with an undefined HAVE_STRDUP thus causing libssh to use its built-in version of strdup.

The code looks as:
#ifndef HAVE_STRDUP
char *
strdup(const char *str)
{
        size_t len;
        char *cp;

        len = strlen(str) + 1;
        cp = malloc(len);
        if (cp != NULL)
                if (strlcpy(cp, str, len) != len) {
                        free(cp);
                        return NULL;
                }
        return cp;
}
#endif

The above is a longer version of 'return NULL'.

Fix: 

Change 'if (strlcpy(cp, str, len) != len)' ->
'if (strlcpy(cp, str, len) != (len-1))'.
How-To-Repeat: #undef HAVE_STRDUP and build libssh.so