clone: make sure we warm the cache after a clone This work around any deviciency/limitation of the clone process. In our case this ensure the persistent nodemap exist with valid content. Ideally, the cloning process would also do "the right thing". However since older server will never be able to do "the right thing". The local workaround will be necessary anyway. I am not worried by the performance impact of this as `hg clone` is non-instant on large repositories where is could matters. Warming the cache if they are already correct is very fast. And if they are not already warm, this seems like a good time to do so. This impact various test as more cache are now warmed sooner, all the change should be harmless. Differential Revision: https://phab.mercurial-scm.org/D9789

persistent-nodemap: remove the "experimental" tag to the feature This has been around for a while and has all the discussed configuration options. Differential Revision: https://phab.mercurial-scm.org/D9764

persistent-nodemap: drop the storage.revlog.nodemap.mode config We now have a new, better, higher level, option. So we can drop the older one as planned. Differential Revision: https://phab.mercurial-scm.org/D9763

persistent-nodemap: add a "abort" option to the slow-path config We make it the default, and document the behavior in the help for the main config option. Differential Revision: https://phab.mercurial-scm.org/D9762

persistent-nodemap: add a "warn" option to the slow-path config And make it the default until we get an abort option. Differential Revision: https://phab.mercurial-scm.org/D9761

persistent-node: check the value of the slow-path config We should probably provide some standard for this in config item, but this is a quest for another adventure. Differential Revision: https://phab.mercurial-scm.org/D9760

persistent-nodemap: add a revlog.storage.persistent-nodemap.slow-path option As discussed during the sprint, we want to prevent user to get an unexpected performance regression when accessing a repository using "persistent-nodemap" without the associated Rust extension. We start by adding a config declaration and some documentation. Since "allow" is the current behavior, we don't need to add any code. The option possible value will come later. Note that we already have a `storage.revlog.nodemap.mode` option, but that option is a bit different. It does some warning and checking at revlog instantiation time. While we want something done at requirements checking time. Since we plan for new names and new config value names, we introduce a new option and will drop the old one later. Differential Revision: https://phab.mercurial-scm.org/D9758

persistent-nodemap: document storage.revlog.persistent-nodemap.mmap=no The feature is gaining public facing document, its options too. Differential Revision: https://phab.mercurial-scm.org/D9757

persistent-nodemap: rename the storage.revlog.nodemap.mmap option Since the feature is publicly known as "persistent-nodemap" this seems better to reference it as "persistent-nodemap" in related config too. So we rename the option to `storage.revlog.persistent-nodemap.mmap`. Differential Revision: https://phab.mercurial-scm.org/D9756

persistent-nodemap: document the feature in `hg help config.format` This is necessary before we advertise the feature more. Differential Revision: https://phab.mercurial-scm.org/D9755