Remaining open source but banning the user who leaks the source code from the repository could work too, no? (the RedHat way).
So as a user, you can start some work based on the insider version and be confident that you will be able to release your work even if the insider version never goes public for some reason, instead of relying on a promise that the code will be released in an open source license.
So as a user, you can start some work based on the insider version and be confident that you will be able to release your work even if the insider version never goes public for some reason, instead of relying on a promise that the code will be released in an open source license.