Correct a format string in virt/baremetal/ipmi.py

"%(err)%s" to "%(err)s"

Change-Id: I5ef1d3218c6121fed7c5d2b4d318da7c6d884776
Merge "Correct a format string in virt/baremetal/ipmi.py"
Merge remote-tracking branch 'citrix/master' into build-temp