tests: add tests of debugmergestate with unresolved/resolved path conflicts I'm about to change `hg debugmergestate` and it broke on these "pu" and "pr" records on my first attempt (D8113), so let's add test coverage. Differential Revision: https://phab.mercurial-scm.org/D8119

mergestate: determine if active without looking for state files on disk I couldn't think of a reason that we need to check state files on disk to determine if a merge is active. I could imagine them being for there for detecting broken state files that would then be cleaned up by some later command, but we always delete the entire `.hg/merge/` tree, so that doesn't seem to be it. The checks were added in 4e932dc5c113 (resolve: abort when not applicable (BC), 2014-04-18). Perhaps there were needed for that and then made obsolete by 6062593d8b06 (resolve: don't abort resolve -l even when no merge is in progress, 2014-05-23). The reason I want to delete the checks is that I think `ms = mergestate.read(repo); ms.active() and ms.local` should be a valid pattern, but it crashes when the merge state file is an empty file if we consider mere presence of the file as "active". Differential Revision: https://phab.mercurial-scm.org/D8118

phabricator: update the protocol documentation The `branch` property wasn't added to the `hg:meta` example when it was added to the metadata in d49ab47be8a6. Additionally, `properties` in the Differential Revision dict is a dinctionary, not a list. While here, also alphabetize the responses from Phabricator because that's how it is being printed with `hg debugcallconduit`, and this makes it easier to compare. Differential Revision: https://phab.mercurial-scm.org/D8170

relnotes: move entry to the right spot It appears a conflict resolution went wrong. Differential Revision: https://phab.mercurial-scm.org/D8151

revlog-compression: release note entry for update the config to be a list I updated the changeset, but forgot to phabsend apparently. Differential Revision: https://phab.mercurial-scm.org/D8165

rust-nodemap: a method for full invalidation This will be used for exceptional operations, such as a `__delitem__` on the `MixedIndex` with Rust nodemap. In principle, `NodeTree` should also be able to forget an entry in an efficient way, by accepting to insert `Element::None` instead of only `Element::Rev(r)`, but that seems really overkill at this point. We need to support exceptional operations such as `__delitem__`, only for completeness of the revlog index as seen from Python. The Python callers don't seem to even really need it, deciding to drop the nodemap unconditionally at at higher level when calling `hg strip`. Also, `hg strip` is very costly for reasons that are unrelated to nodemap aspects. Differential Revision: https://phab.mercurial-scm.org/D8098