# Mercurial 5.7 (2021-01-29)

This is an overview of the 5.7 release.
## New Features 

- There is a new config section for templates used by hg commands. It called `[command-templates]`. Some existing config options have been deprecated in favor of config options in the new section. These are:
   `ui.logtemplate` to `command-templates.log`,

   `ui.graphnodetemplate` to `command-templates.graphnode`,

   `ui.mergemarkertemplate` to `command-templates.mergemarker`,

   `ui.pre-merge-tool-output-template` to `command-templates.pre-merge-tool-output`.

- There is a new set of config options for the template used for the one-line commit summary displayed by various commands, such as `hg rebase`. The main one is `command-templates.oneline-summary`. That can be overridden per command with `command-templates.oneline-summary.<command>`, where `<command>` can be e.g. `rebase`. As part of this effort, the default format from `hg rebase` was reorganized a bit.

- `hg purge` is now a core command using `--confirm` by default.

- `hg diff` and `hg extdiff` now support `--from <rev>` and `--to <rev>` arguments as clearer alternatives to `-r <revs>`. `-r <revs>` has been deprecated.

- The memory footprint per changeset during pull/unbundle operations has been further reduced.

- There is a new internal merge tool called `internal:mergediff` (can be set as the value for the `merge` config in the `[ui]` section). It resolves merges the same was as `internal:merge` and `internal:merge3`, but it shows conflicts differently. Instead of showing 2 or 3 snapshots of the conflicting pieces of code, it shows one snapshot and a diff. This may be useful when at least one side of the conflict is similar to the base. The new marker style is also supported by "premerge" as `merge-tools.<tool>.premerge=keep-mergediff`.

- External hooks are now called with `HGPLAIN=1` preset.  This has the side effect of ignoring aliases, templates, revsetaliases, and a few other config options in any `hg` command spawned by the hook.  The previous behavior can be restored by setting HGPLAINEXCEPT appropriately in the parent process.
   See `hg help environment` for the list of items, and how to set it.

- The `branchmap` cache is updated more intelligently and can be significantly faster for repositories with many branches and changesets.

- The `rev-branch-cache` is now updated incrementally whenever changesets are added.


## New Experimental Features 

- `experimental.single-head-per-branch:public-changes-only` can be used restrict the single head check to public revision. This is useful for overlay repository that have both a publishing and non-publishing view of the same storage.


## Backwards Compatibility Changes 

- `--force-lock` and `--force-wlock` options on `hg debuglock` command are renamed to `--force-free-lock` and `--force-free-wlock` respectively.


## Internal API Changes 

- `changelog.branchinfo` is deprecated and will be removed after 5.8. It is superseded by `changelogrevision.branchinfo`.
