I upgraded to sendmail-8.10.1-9.i386.rpm. Now, as soon as fetchmail try to connect to sendmail, it is refused: fetchmail send a SYN on the lo interface and receives a RST. I downgraded to the previous rawhide version of sendmail, and it works as before.
Per default sendmail now doesn't listen on the smtp port. Configure fetchmail to use /usr/sbin/sendmail instead. Or change /etc/sysconfig/sendmail.