Summary:
The emission of the signal KisNodeProgressProxy::percentageChanged due to
KisBusyProgressIndicator::endUpdatesBeforeDestroying()
KisBusyProgressIndicator::Private::stopProgressReport()
KisNodeProgressProxy::setRange(int, int)
resulted in a temporary KisNodeSP being created, which called ref() and
deref() on the KisNode object, whose KisShared part already was at 0
ref count, which results in deref() to trigger another delete call
on the KisNode.

BUG: 363416
BUG: 363470

Fixes T2393

Test Plan: KisFileLayerTest no longer fails, other tests still as before.

Reviewers: #krita:_next, rempt, dkazakov

Differential Revision: https://phabricator.kde.org/D1695