header_minlen    1489 iseq.c             if ((l = RSTRING_LEN(str)) < header_minlen) {
header_minlen    1490 iseq.c         	rb_str_resize(str, header_minlen);
header_minlen    1491 iseq.c         	memset(RSTRING_PTR(str) + l, '=', header_minlen - l);