In 1.15, a feature to Merge pod templates definitions from yaml has been added.
This is a change from the previous behaviour, where the yaml definition from the last pod template in the hierarchy was shadowing any inherited pod template. In some case, this could cause some surprises when upgrading.
The intent here is to make this feature backward compatible by providing users with the choice to merge or override yaml fragment from parent when defining a pod template.
The default behaviour would be to override, to achieve backward compatibility with previous versions.