While the code path that queries the monitor allocates a separate copy
of the 'group_name' string the path querying the config would not copy
it. The call to virTypedParameterAssign would then steal the pointer
(without clearing it) and the RPC layer freed it. Any subsequent call
resulted into a crash.

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1433183