We've managed to avoid bumping core.repositoryformatversion for the past 10 years, which is great. But I think there are some looming features that are going to need it. The most obvious one is changing the ref storage, where we need some way to tell older gits "no, please don't think that taking 'refs/heads/foo.lock' is sufficient to actually lock". The first patch in this series is an attempt to pave the way for version bumps like this in as painless a way as possible, by letting us mark incompatible "extensions" by name. That way we can version things like "how do you lock a ref" independent of the main repositoryformatversion setting (just like we do for index version, for example). See the explanation in the first patch for more details. The second patch shows another use of the "extension" feature to provide safety in shared-object repos against older versions of git. [1/2]: introduce "extensions" form of core.repositoryformatversion [2/2]: introduce "preciousObjects" repository extension -Peff -- To unsubscribe from this list: send the line "unsubscribe git" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html