This bug was found by examination of the source. During freeing of the data structure used to hold the definition for host bridge interfaces (those created via the iface-define command), a free of the delay string was inadvertently omitted.
This has been committed upstream 6328dfcb670953c17e6061fae02417f8756726bb
The same patch has also been posted for RHEL6.
This issue has been proposed when we are only considering blocker
issues in the current Red Hat Enterprise Linux release.
** If you would still like this issue considered for the current
release, ask your support representative to file as a blocker on
your behalf. Otherwise ask that it be considered for the next
Red Hat Enterprise Linux release. **
libvirt-0_8_1-21_el6 has been built in RHEL-6-candidate with the fix.
Red Hat Enterprise Linux 6.0 is now available and should resolve
the problem described in this bug report. This report is therefore being closed
with a resolution of CURRENTRELEASE. You may reopen this bug report if the
solution does not work for you.