Sorry, I swear, that the test project didn't have a wrapper at all (despite the wrapper task in the build.gradle file, the task was not run, you'll see there's no wrapper properties in the project.
My guess is that I probably had the version set to M3 in global workspace preferences without knowing it. It tends to get set to M3 because it is the only way I can work with some projects that don't have the wrapper, yet only work with M3.
One thing though... I guess this is fixed in the gradle distro not the api, so we are still a little stuck until we can actually expect people to move away from using M3.
In fact the test project I am using as a regression tests for functionality depending on running the eclipse tasks is spring-security and it only works with M3 so far.
Is there any chance this could be fixed on the API side? I.e. fixed in a way that it would work with M3 if the API version is recent enough.
Otherwise in practice https://issuetracker.springsource.com/browse/STS-2085 and https://issuetracker.springsource.com/browse/STS-2091 will still not work reliably for any real project I have available for testing this functionality.