Bug 900216 - Node is not getting roles during discovery

Having the error  "FATAL -- : Node exists without role!!" makes Suse Cloud Crowbar webpage display "We're sorry something went wrong".
This is a workaround to get the webpage functional again, before finding
why nodes are not getting roles every time.
Bug address: https://bugzilla.novell.com/show_bug.cgi?id=900216

added bugzilla bug link for Bug 900216