Patch taken from https://bugs.gentoo.org/626464
This is a temporary fix. The real bug is in qtsql and needs to be fixed there.

Downstream bug reports:
https://bugs.kde.org/show_bug.cgi?id=383991
https://bugreports.qt.io/browse/QTBUG-63108

--- akonadi-17.04.3/src/server/storage/dbconfigmysql.cpp        2017-08-11 23:29:02.088613966 +0800
+++ akonadi-17.04.3/src/server/storage/dbconfigmysql.cpp        2017-08-11 23:22:18.808432643 +0800
@@ -492,7 +492,7 @@
         }
     }

-    QSqlDatabase::removeDatabase(initCon);
+    //QSqlDatabase::removeDatabase(initCon);
     return success;
 }