regression: kio FTBFS on i386 and armhf with cmake >= 3.13

Version: 3.13.3-1
Release: Disco proposed

With cmake >= 3.13 the KDE Framework Kio fails to build on i386 and armhf with the error shown below:

Confirmed in PPA build on next Kio version: (link removed as succeeded with 3.12.3 after 3.13.1 was removed from proposed.)

and a regression against the current version in disco -release

http://autopkgtest.ubuntu.com/packages/k/kio/disco/i386

Also confirmed in disco chroot, and bisected to the upstream merge of the follow group of commits:

https://gitlab.kitware.com/cmake/cmake/commit/c31d9f1c30bddef091517a777936362a403b49b2

*** build error **

In file included from /<<PKGBUILDDIR>>/src/core/slaveinterface.cpp:441:
/<<PKGBUILDDIR>>/obj-i686-linux-gnu/src/core/KF5KIOCore_autogen/include/moc_slaveinterface.cpp: In static member function ‘static void KIO::SlaveInterface::qt_static_metacall(QObject*, QMetaObject::Call, int, void**)’:
/<<PKGBUILDDIR>>/obj-i686-linux-gnu/src/core/KF5KIOCore_autogen/include/moc_slaveinterface.cpp:171:22: error: ‘class KIO::SlaveInterface’ has no member named ‘open64’; did you mean ‘open’?
         case 10: _t->open64(); break;
                      ^~~~~~
                      open
/<<PKGBUILDDIR>>/obj-i686-linux-gnu/src/core/KF5KIOCore_autogen/include/moc_slaveinterface.cpp:280:84: error: ‘open64’ is not a member of ‘KIO::SlaveInterface’
             if (*reinterpret_cast<_t *>(_a[1]) == static_cast<_t>(&SlaveInterface::open64)) {
                                                                                    ^~~~~~
/<<PKGBUILDDIR>>/obj-i686-linux-gnu/src/core/KF5KIOCore_autogen/include/moc_slaveinterface.cpp: At global scope:
/<<PKGBUILDDIR>>/obj-i686-linux-gnu/src/core/KF5KIOCore_autogen/include/moc_slaveinterface.cpp:475:6: error: no declaration matches ‘void KIO::SlaveInterface::open64()’
 void KIO::SlaveInterface::open64()
      ^~~
/<<PKGBUILDDIR>>/obj-i686-linux-gnu/src/core/KF5KIOCore_autogen/include/moc_slaveinterface.cpp:475:6: note: no functions named ‘void KIO::SlaveInterface::open64()’
In file included from /<<PKGBUILDDIR>>/src/core/slaveinterface.cpp:19:
/<<PKGBUILDDIR>>/src/core/slaveinterface.h:102:22: note: ‘class KIO::SlaveInterface’ defined here
 class KIOCORE_EXPORT SlaveInterface : public QObject
                      ^~~~~~~~~~~~~~