Comment # 1 on bug 1141604 from Wolfgang Bauer

According to https://bugs.kde.org/show_bug.cgi?id=409753 (which looks very much
like your bug), reverting this commit should fix it:
https://cgit.kde.org/akonadi.git/commit/?id=74aed9542ba1ff1e6e93a550c42869647c4eba8e

No need for downgrading the whole package.

We don't necessarily need this change anyway, as we reverted the incompatible
change in Qt.