Here is a reply from "redhat" (supplier of python-bugzilla tool) that
"*there is no wrapper for what I want. The bugzilla XMLRPC call is 'fields' for bugzilla4+
http://www.bugzilla.org/docs/4.4/en/html/api/Bugzilla/WebService/Bug.html#fields
It can be a work around this by accessing the xmlrpc proxy directly and handling the calls yourself, ex:
import bugzilla
bz = bugzilla.Bugzilla(url="https://bugzilla.kernel.org")
print bz._proxy.Bug.fields({"names" : ["rep_platform"]})
Of course, that's not supported, so it could stop working on you one day, but for personal scripts and stuff it's an alternative.*"