largefiles: drop the override for 'fetch' The fetch extension has been calling cmdutil.bailifchanged() since a014fdc97154, so this is redundant. Add test coverage to prevent regression. It doesn't look like there is any testing for fetch with largefiles.

rebase: ignore negative state when updating back to original wc parent The state mapping also contains some magic negative values (detached parent, ignored revision). Blindly reading the state thus lead to unfortunate usage of the negative value as an update destination. We now filter them out. We do a minor alteration of the test to catch this.

bundle2-push: provide transaction to reply unbundler This patch series is intended to allow bundle2 push reply part handlers to make changes to the local repository; it has been developed in parallel with an extension that allows the server to rebase incoming changesets while applying them. This diff adds an experimental config option "bundle2.pushback" which provides a transaction to the reply unbundler during a push operation. This behavior is opt-in because of potential security issues: the response can contain any part type that has a handler defined, allowing the server to make arbitrary changes to the local repository.