Comment # 15 on bug 1056937 from Zhao Qiang ������

KDE and Plymouth share the same frame-buffer device because Sddm lack of
Plymouth controlling logic, A reference is GDM's code:
https://github.com/GNOME/gdm/blob/master/daemon/gdm-manager.c#L142-#L208

Additionally, openSUSE is unlike other releases or distros, it boots at tty1
but launch desktop at tty7, this display VT switching makes the "race" problem
even more obvious.

The modification will add code to quit Plymouth inside Sddm, 
This problem only effects openSUSE KDE desktop and it doesn't cause the isolate
failed or other problem, So I will work in this when I have time. If anyone
feels this problem very emergency, please raise the bug priority.

Thanks!