SvUPGRADE(sv, SVt_PV);
(void)SvUPGRADE(sv, SVt_PV);
static apr_bucket *mpxs_APR__Bucket_new(pTHX_  SV *classname, apr_bucket_alloc_t *list,                                        SV *sv, apr_off_t offset, apr_size_t len){    apr_size_t full_len;    if (sv == Nullsv) {        sv = newSV(0);        SvUPGRADE(sv, SVt_PV);    }    (void)SvPV(sv, full_len);    if (len) {        if (len > full_len - offset) {            Perl_croak(aTHX_ "APR::Bucket::new: the length argument can't be"                       " bigger than the total buffer length minus offset");        }    }    else {        len = full_len - offset;    }        return modperl_bucket_sv_create(aTHX_ list, sv, offset, len);}