To avoid having packagers creating tarballs of the entire git repo for sources, we should have a list of projects, and their build timestamp pre-generated. Looking at https://bugs.eclipse.org/bugs/show_bug.cgi?id=405042 , this will likely have to be implemented in Fedora.
As a workaround for now, packagers of eclipse plugins could remove the usage of tycho-buildtimestamp-jgit plugin so that the default is used.
I'm going to close this as 'WONTFIX' for now since matching the build timestamps could cause issues with simple release bumps.