Created attachment 830976 [details]
y2log

I do a normal installation of 15.2. After I do the usual selections, I arrive
at the final Installation Setting screen.
In the Network Configuration section I have:

Not configured yet.
   Hostname: Set by DHCP

I click on the Network Configuration link and I go to the Network Setting
screen.
I click on the Hostname/DNS tab
In the Hostname file I put my hostname
and for Set Hostname via DHCP I select No
After I click on Next, the Saving Network Configuration screen appears, showing
the steps yast is doing while setting the network and saving the configuration.
Then the Installation Setting screen is back.
However, in the Network Configuration section I still have:

Not configured yet.
   Hostname: Set by DHCP

despite the changes I made. And if I go again to the Network Setting
Hostname/DNS tab I can see my new choice in the hostname field.
But if I continue the installation, after reboot the system indeed does not
have the hostname set with my choice.
In 15.1 these steps used to work, but not in 15.2
Attached are the y2logs.

The problem seems to be in sysconfig/config_writer.rb but I could not figure
out where exactly.