Fix missing merge after release in intermediate mode

Steps to reproduce:

• setup a project where branch management is set to "intermediate"
• make changes on your work branch
• merge these changes to master
• perform a release

==> after this, there are changes to push to master: these changes are linked to the release (the next version is kept in application.xml).

These changes should be pushed to master by Studio automatically after the release.

Note that releases done from a work branch will be common to all branches on the project: there are potential conflicts if 2 users release their branch around the same time and the "next version" is not shared between the branches, it seems the same release name could be used (overriding the previous release, maybe)