Comment # 17 on bug 102349 from Ilia Mirkin

(In reply to Christian Tosta from comment #16)
> Not fixed in Mesa 18.2.8 for Fedora 29. Plasmashell keeps segfaulting.
> Screen turns black with only the cursor. Konsole and other programs 
> runs fine, except for plasmashell and sddm-greeter.

Nor is it expected to be fixed in that version. I pushed the changes to master,
you'll have to build that (or get something for your distro which follows the
latest development).