Comment # 5 on bug 1011094 from Wolfgang Bauer

(In reply to Ignacio Taranto from comment #4)
> kdoctools was not installed by default, after installed the icons are fixed
> in khelpcenter5.

So we miss a dependency, we should better make sure then that kdoctools is
installed...

> But the icons in khelpcenter (also installed by default in leap 42.2) are
> now somehow a mix between breeze and oxygen, although my global
> configuration is set to breeze-dark.

Likely unrelated (to khelpcenter5 anyway), try to delete the icon cache
(~/.cache/icon-cache.kcache).

I'm quite sure that's the same problem as mentioned in bug#1000519.