exchange: refactor control flow of _getbundlechangegrouppart() The use of early return makes the control flow of this function much easier to reason about IMO. Differential Revision: https://phab.mercurial-scm.org/D4010

exchange: move _computeellipsis() from narrow This is also referenced as part of the narrow changegroup code and therefore needs to move to core before we can integrate the narrow changegroup code into core. Differential Revision: https://phab.mercurial-scm.org/D4009

exchange: move narrow acl functionality into core This function is called by the custom changegroup generation code in the narrow extension. I want to move that changegroup code into core. That means we need to move this function. The code is kinda hacky in that assumes existence of REMOTE_USER, which is only present on authenticated HTTP requests. I've added a comment indicating that. Differential Revision: https://phab.mercurial-scm.org/D4008

exchange: move disabling of rev-branch-cache bundle part out of narrow I'm attempting to refactor changegroup code in order to better support alternate storage backends. The narrow extension is performing a lot of monkeypatching to this code and it is making it difficult to reason about how everything works. I'm reasonably certain I would be unable to abstract storage without requiring extensive rework of narrow. I believe it is less effort to move narrow code into core so it can be accounted for when changegroup code is refactored. So I'll be doing that. The first part of this is integrating the disabling of the cache:rev-branch-cache bundle2 part into core. This doesn't seem like it is related to changegroup, but narrow's modifications to changegroup are invasive and also require taking its code for bundle generation and exchange into core in order for the changegroup code to work. Differential Revision: https://phab.mercurial-scm.org/D4007

dispatch: show a short error message when invalid global option given Similar reasoning as the previous patch. Differential Revision: https://phab.mercurial-scm.org/D4025

dispatch: don't show list of commands on bogus command If a command is ambiguous, you get this: $ hg ve hg: command 've' is ambiguous: verify version [255] If you typo a command, you get this: $ hg comit hg: unknown command 'comit' (did you mean one of commit, incoming, mycommit?) [255] But if you completely mistype a command so it no longer looks like any existing commands, you get a full list of commands. That might be useful the first time you use Mercurial, but after that it's probably more annoying than help, especially if you have the pager enabled and have a short terminal. Let's instead give a short hint telling the user to run `hg help` for more help. Differential Revision: https://phab.mercurial-scm.org/D4024