What does your change have to do with the boo#1084909 bug?
And why should the host be empty?
And if not, then it is always different in any case.
How should the bug above be fixed by this?
The bug entry criticizes exactly the bug.
First, I have not seen such a change anywhere and secondly, I do not understand the sense behind it at all.
For my understanding, the bug is only active through your change.
Not before, because before the host was always called OBS.

I have the feeling that you read the diff backwards. The change is to always use "OBS" as the hostname embedded in the binary instead of the %_buildhost.

I have meanwhile found that we can also completely omit the line and still be reproducible.