See KCMHelpCenter::startIndexProcess in runtime/khelpcenter/kcmhelpcenter.cpp.
runtime/khelpcenter/kcmhelpcenter.cpp is not compiled in kde-base/khelpcenter
Sorry I was wrong. Fixed in upcoming versions.
please be more specific, which versions are suffering from this bug and which ones are fixed?
Fixed in the overlay. Did not really bother about the tree versions since noone else even noticed the poblem.