rewriting: add an option for rewrite commands to use the archived phase Using the archived phase for cleanup provide the same effect than stripping, but in a faster, append-only way. We keep the feature experimental for now until it gets a bit more testing.

strip: introduce a soft strip option This is the first user-accessible way to use the archived phase introduced in 4.8. This implements a feature discussed during the Stockholm sprint, using the archived phase for hiding changesets. The archived phase behaves exactly as stripping: changesets are no longer visible, but pulling/unbundling them will make then reappear. The only notable difference is that unlike hard stripping, soft stripping does not affect obsmarkers. The next changeset will make use of the archived phase for history rewriting command. However, having a way to manually trigger the feature first seems a necessary step before exposing users to this phase; there is a way to un-archived changesets (unbundling), so there must be a way to archive them again. Adding a flag to strip is a good way to provide access to the feature without taking a too big risk on the final UI we want. The flag is experimental so it won't be exposed by default. Using the archived phase is faster and less traumatic for the repository than actually stripping changesets.

branchcache: move loading of branch names and nodes into it's own function This will help me in implementing lazy loading of the branchcache in upcoming patches. Differential Revision: https://phab.mercurial-scm.org/D6023

bundle2: don't send "shared" requirement when cloning from a share Differential Revision: https://phab.mercurial-scm.org/D5985

tests: demonstrate failure when cloning from a share via bundle2 Differential Revision: https://phab.mercurial-scm.org/D5984

mq: disable qrecord during histedit (issue5981) qrecord during histedit may lead to deadlock-like situations. qpop will throw an error on called during histedit even after qrecord-ing those changes. This patch makes qrecord to abort on histedit. Differential Revision: https://phab.mercurial-scm.org/D5997

committablectx: move status-related methods closer together The modified()/added()/removed()/deleted() clearly belong very close to status(). I separated them in committablectx by the new p[12]copies() methods. This brings the close again. Sorry about the churn. Differential Revision: https://phab.mercurial-scm.org/D5996

tests: add test for hg-test-mode emacs code This is just coverage for the compilation-mode support, but that was enough of a hassle that I wanted to have it covered somehow. Test methodology is _extremely_ cargo-culted from the test for compilation-mode in emacs, so I still have no idea what I'm doing. Differential Revision: https://phab.mercurial-scm.org/D6003