worker: call selector.close() to release polling resources

release: merge default into stable for 4.7 release freeze

histedit: drop --no-backup option Dropping this option because now we have a better option than passing --no-backup flag every time, now user can set a config in hgrc: [ui] history-editing-backup = False This config aims to operate on every history editing command and it is still work in progress. As yuya suggessted it probably to late to add full support this config, so making this as an experimental config. Differential Revision: https://phab.mercurial-scm.org/D3965

aggressivemergedelta: document rename and move to `revlog` section The config does not follow our naming guideline and "Aggressive" is probably a word to keep away from users. The option does not truly fit in the `format` section. It can be turned on and off for existing repository without much consequence regarding compatibility. A new `revlog` option is created to control behavior related to revlog writing and reading. We can see multiple other config options that could be migrated there. * format.maxchainlen * experimental.mmapindexthreshold * experimental.sparse-read.density-threshold (in an updated form) * experimental.sparse-read.min-gap-size (in an updated form) In addition, we can foresee at least a couple of sparse-revlog related option coming too (to reduce delta chain length and increase snapshot reuse) These two extra options might fit there too. Unless we want to create a section dedicated to caches and performance. * format.chunkcachesize * format.manifestcachesize For now, we only migrate `optimize-delta-parent-choice` since it is getting out of experimental. It is too close to the release to move the other one. In addition, we still lack proper the prioritization of alias that would help renaming them without bad consequence for users. (Not fully happy about the `revlog` name but could not find better).