shelve: bundle using bundle2 if repository is general delta (issue4862) This will prevent expensive delta computation on bundling and is similar to what we do for strip backup.

shelve: move changegroup generation inside writebundle We will generate different changegroup if general delta is enabled so we gather this in the lower level function. There wasn't any good reason to have it in the main code anyway.

shelve: compress on-disk bundle Shelve is using 'HG10UN' bundle for no obvious reason. Changing this to 'HG10BZ' as we do for other bundle stored on disk.

merge with stable

notify: fix fromauthor setting for 'incoming' hook type (issue4194) Set the author field in notification emails for the 'incoming' hook type in addition to 'changegroup' and 'outgoing' types.

templater: protect word() from crashing on out of range negative value The function isn't documented to work with negative values at all, but it does, which can be useful. However, the range check didn't account for this.

commands: add a new debug command to print merge state We're going to be extending the merge state very soon, and this will give us a way to test all that.

merge.mergestate: factor out code to validate v1/v2 records We're going to need this in another place in upcoming patches.

localrepo: prevent wlock from being inherited when a transaction is running Review feedback from Pierre-Yves David. A separate line of work is working to ensure that dirstate writes are written to a separate 'pending' file while a transaction is active. Lock inheritance currently conflicts with that, so dodge the issue by simply preventing inheritance while a transaction is running. Custom merge drivers aren't going to run inside a transaction, so this doesn't affect that.

lock: add a way to prevent locks from being inherited We want to prevent locks from being inherited sometimes (e.g. when there's a currently running transaction, which will break a lot of assumptions we're making in here.)