The python test test_qgsrelation.py was failing for misterious reasons
(the very same test was passing if run from QGIS application), I tracked
the issue down to the addition of QgsOptionalExpression mCollapsedExpression;
in QgsAttributeEditorContainer.
The new c++ test replicates the python test and make sure there are no
problems with the change style operation.
values should be reused when creating new features
While there has long been a global option that causes ALL field
values for ALL layers to be remembered and reused during a QGIS
session when creating new features, this new setting offers
per-layer, per-field control over whether values should be
reused.
It allows for finer control over form behavior, where eg some
values may be desirable to reuse but others should be cleared
or set from default value expressions.
