RHEL Engineering is moving the tracking of its product development work on RHEL 6 through RHEL 9 to Red Hat Jira (issues.redhat.com). If you're a Red Hat customer, please continue to file support cases via the Red Hat customer portal. If you're not, please head to the "RHEL project" in Red Hat Jira and file new tickets here. Individual Bugzilla bugs in the statuses "NEW", "ASSIGNED", and "POST" are being migrated throughout September 2023. Bugs of Red Hat partners with an assigned Engineering Partner Manager (EPM) are migrated in late September as per pre-agreed dates. Bugs against components "kernel", "kernel-rt", and "kpatch" are only migrated if still in "NEW" or "ASSIGNED". If you cannot log in to RH Jira, please consult article #7032570. That failing, please send an e-mail to the RH Jira admins at rh-issues@redhat.com to troubleshoot your issue as a user management inquiry. The email creates a ServiceNow ticket with Red Hat. Individual Bugzilla bugs that are migrated will be moved to status "CLOSED", resolution "MIGRATED", and set with "MigratedToJIRA" in "Keywords". The link to the successor Jira issue will be found under "Links", have a little "two-footprint" icon next to it, and direct you to the "RHEL project" in Red Hat Jira (issue links are of type "https://issues.redhat.com/browse/RHEL-XXXX", where "X" is a digit). This same link will be available in a blue banner at the top of the page informing you that that bug has been migrated.

Description
The error message need to be improved while save one guest with pci device

Version:
libvirt-0.10.2-24.el6.x86_64
qemu-kvm-0.12.1.2-2.402.el6.x86_64

How reproducible:
100%

Steps to Reproduce:
1. prepare one guest with pci device
# virsh dumpxml a|grep hostdev -A 5
    <interface type='hostdev' managed='yes'>
      <mac address='52:54:00:43:0d:0b'/>
      <source>
        <address type='pci' domain='0x0000' bus='0x03' slot='0x10' function='0x1'/>
      </source>
      <alias name='hostdev0'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x07' function='0x0'/>
    </interface>

2. save the guest
# virsh save a a.save
error: Failed to save domain a to a.save
error: internal error unable to execute QEMU command 'migrate': An undefined error has ocurred

3. find one rhel7 host, save one guest with the pci device, it will report the error like the following one:
# virsh save a a.save
error: Failed to save domain a to a.save
error: Requested operation is not valid: domain has assigned non-USB host devices

Actual results:
as step 2

expect results:
The error message in step 2 should be improved like step 3, should delete ": An undefined error has ocurred". 

Additional info:

*** This bug has been marked as a duplicate of bug 874418 ***