Tag remove preprocessor #640
Historically with IPython we did feature releases like '6.0' and bugfix rollups like '6.1', but since the big split we've tended more towards semver style versioning, so we increment the major version to indicate breaking changes. To some extent this is up to the people working on each individual project, though.
I'm not the biggest fan of semver - I think it ignores the complexity of real development, where almost every change can break something - but I know that when we're aiming for a new .0 release, it tends to become a Big Deal, and everyone wants their thing backported to the previous series. So I'm inclined to leave 6.0 until we actually want to break something.