Description of problem:
When upgrading an oVirt setup to 3.5, one of the features that one would like
to setup is the new JSON RPC.

The problem is that once the default cluster has been moved to 3.5
compatibility and the vdsm on the hosts are 4.16.1-0.gita4d9abf, if I put the
hosts in maintenance, going to the "advanced" section of the host editing
dialog does not let me change the communication to jsonrpc

Version-Release number of selected component (if applicable):

vdsm-4.16.1-0.gita4d9abf,
ovirt-engine-3.5.0-0.0.master.20140722232056.git8e1babc.fc19.noarch

How reproducible: 100%


Steps to Reproduce:
0. Put the host in maintenance
1. Upgrade setup from 3.4 to 3.5 (both engine and vdsm machines)
2. Go to the Host edit dialog
3. Tick "advanced parameters"

Actual results:
No possibility to change to json rpc for communication with the host


Expected results:
The same options to set the connectivity to use JSON rpc as when adding a new
host are present


Additional info:
The workaround is to delete the host and add it again, but it is very
cumbersome.